Excerpt from Memorial Pamphlet Containing Certain Drawings of Medusae

Numerous short, chitmous spines are developed upon the crust which covers the fibers, and thus we find the polypites arising from a flat, spinous base which adheres to the surface on which the colony is growing. The colony is composed of two kinds of hydranths: sterile feeding-polypites, and reproductive gonostyles. The sterile teedingpolypites are spindle-shaped, being about twice as wide near the oral circlet of tentacles as they are at the base. They have 12 to 16 straight, stiff tentacles. The mouth is situated at the apex of a dome-shaped proboscis. They are very contractile and may vary in length from about 5 to 15 mm. The reproductive polypites, or gonostyles, are frequently exactly similar in size and shape to the feeding-polypites, and, in fact, are probably merely feeding-polypites which have developed medusa-buds Differences between European and American medusa of Podocoryne carnta. ItTfi 1 Tn other instances the gonostyles are smaller and more slender, and possess not more than 4 to 8 tentacles (see g, fig.2). The medusa-buds arise from a zone which is slightly below the circlet of oral tentacles. From 4 to 8 of these buds are usually to be seen upon each gonostyle. According to Martha Bunting, 1894, it appears that the medusa-bud arises as an outpushing of both entoderm and ectoderm of the gonostyle. As the bud progresses in its development, we find the ova in the entoderm of the manubrium. When a later stage has been reached they migrate from the entoderm into the ectoderm. The spermatozoa, on the other hand, originate in the ectoderm of the inanubrium, as was shown by Weismann, 1883. When set free the medusa usually has 8 tentacles:4 radial and 4 interradial. The radial tentacles are usually better developed than the interradial and in some individuals there are but 4 tentacles at the time of liberation, the interradial ones not yet being developed. It is remarkable that while in some stocks of Podocoryne the medusae are set free in an immature state, in others the medusae are mature when liberated, the manubnum being distended with sperm or ova, which are discharged almost immediately after the medusa is set free. It is possible, as Allman, 1871, suggests, that this difference may be due to the influence of local conditions, which may be favorable in the one case and not so in the other to an advanced development of the medusa. Krohn, 1851, and Loven, 1857, have observed stocks of the European form of Podocoryne which were setting free mature medusa?. Indeed, we appear to have a parallel case in Sarsia on the Massachusetts coast, where immature medusae are liberated during the early spring months, whereas the medusae become ripe, discharge their genital products, and wither upon the hydroid stock in May. Good figures of Podocoryne stocks which are setting tree immature medusae have been given by Sars, 1846, Hincks, 1868, Allman, 1871, etc. When set free the medusae commonly have 8 tentacles, 4 radial and 4 interradial. The radial tentacles are usually more advanced than the interradial, and in some few individuals there is no trace of interradial tentacles at the time when the medusa is liberated. The manubrium is short and fusiform and the mouth is surrounded by 4 radially situated, oral tentacles, each of which terminates in a knob-shaped cluster of nematocysts. When set free the medusa is about 0.5 to 0.6 mm. in height. In those medusae which are set tree in an immature condition there are at first 8 tentacles, but these increase in number as growth proceeds and finally, when the medusa is about 3.5 mm. in height, there are usually about 32 tentacles, 8 in each quadrant. The manubrium ot the young, immature medusa is slender and fusiform, while in those medusae which are set tree in a mature state it is globular and greatly distended with the genital products. The ectoderm ot the hydroid is slightly bluish and translucent