﻿April, 1857.] 



ELLIOTT SOCIETY. 



147 



could not, however, have been much further advanced in the Sep- 

 tember specimens, since after falling to the bottom of the vessel, 

 they never rose from it. 



Whether this is really Guilding's species of the Caribbean sea, 

 or a new one, I cannot say, having never seen either Guilding's 

 figure or description. That description is very meagre, as given 

 by Lesson. I have, for the present, attributed to it Guilding's 

 name, from unwillingness to create a species without an actually 

 known difference of character, and because, as before stated, the 

 species is brought to us by prolonged southerly winds, thus com- 

 ing from the neighborhood of Guilding's Polybraehionia linneana. 

 However I am, despite this reason, inclined to think it a new spe- 

 cies. 



3rd Group. TUBULARTD^. Johnston. 



I have included in this group all those Endostomata whose lar- 

 vse have the tentacula distributed in one or two regular whorls, in- 

 cluding thus Pennaria and Stauridium, besides Eudendrium, while 

 a provisional position is also given here to Hydractinia, on whose 

 probable affinities I shall venture a few remarks further on. 



The Medusae of this group are distinguished by a smooth exte- 

 rior to the bell, or a peculiar ornamentation, like that described in 

 Chrysomitra, viz : rows of thread-cells, extending upwards from 

 the bell-margin towards the vertex of the bell. This is very dif- 

 ferent from the scattered condition of the thread-cells among Cory- 

 nidse. For, as will be seen in the representation of this struc- 

 ture in Gegenbaur's figures of Chrysomitra and Zanclea, in Van 

 Beneden's figures of the medusa of Tubularia, (Les Tubulaires, 

 pi. 5, fig. 20-25,) and in the figures of Willsia and Zanclea of this 

 work, Cpl. 9, f. 10, pi. 8, f. 4 x.,) the thread cells in this case are 

 not only arranged in rows, but these rows are inclosed within a 

 delicate bounding membrane. In Pennaria proper, these rows of 

 thread-cells appear to be replaced by rows of pigment cells, occu- 

 pying the same position; while among the Hippocrenidae, the ex- 

 ternal surface appears to be smooth and unornamented throughout. 

 Mehrtens, however, described certain villosities near the bell-mar- 

 gin of his species of Hippocrene, and it seems to be in this posi- 

 tion that the thread-cell-rows first appear, afterward growing up- 

 wards towards the summit, which they seldom actually reach. 

 There are besides various complications of the principal organs, 

 which, though not constant among the Medusae here brought to- 



