GEMMARIA CLADOPIIORA. 



185 



but is curved in tlie opposite direction ; near the ujaper bend of the 

 chymiferous tubes, it runs up into a point, making a sliarp and deep 

 groove round the projection of the Fig. 30s. 



spherosome; the chymiferous tubes 

 (c', Fig. 308), as well as the circu- 

 lar tube, are very broad (Fig. 308), 

 opening into a conical digestive 

 cavity, which at its base occupies 

 nearly the whole width of the up- 

 per part of the inner bell ; this cav- 

 ity tapers gradually till it reaches 

 the level of the veil, where the 

 edges flare a httle ; the extremity 

 of the proboscis has a tendency to be slightly drawn in, so that the 

 opening of the cavity is flanked by the pouches formed by the partial 

 contraction of a portion of the walls ; the walls are thick, and open into 

 Jig. 309. a quadrangular mouth (Fig. 309), surrounded by a 



couple of concentric rows of large lasso-cells ; simi- 

 lar large cells extend on the outside of the chymif- 

 erous tubes, more than half-way up the sphero- 

 some. (Fig. 308.) 



The tentacles are broad and thick, two of them 

 being more developed than the others (Fig. 307) ; 

 they are of a light-brown color, with orange pig- 

 ment-cells at the base ; the knobs of lasso-cells are attached to quite 

 long stems (Fig. 310); the walls of the digestive cavity are rig. 310. 

 thick ; the ovaries are placed in the upper part of the proboscis. 

 Found at Naliant in the beginning of August. When at rest, 

 the tentacles are stretched out very obliquely from the bell, 

 and they often remain perfectly motionless iu this position ; 

 the Medusae are quite rapid in their movements. (Fig. 307.) 



Professor Clark discovered at Nahant a Hydroid closely resembling 

 the Coryne iviplexa of Alder, and which I suspect will prove to be the 

 nurse of our Gemmaria ; this would be in accordance with the observa- 

 tions of Allman on the development of Zanclea from Coryne imjilexa. 

 Massachusetts Bay, Nahant (A. Agassiz). 

 Cat. No. 363, Nahant, 1862, A. Agassiz. Medusa. 

 ? Cat. No. 63, Nahant, May, 1862, H. J. Clark. Hydrarium. 

 Museum Diagram, No. 20, after A. Agassiz. 



Fig. 308. Quarter of the disU of Gr. cladophora, seen from the abactinal pole, c, circular 

 tube ; c', chymiferous tube; b, sensitive bulb, having a great accumulation of pigment and lasso 

 cells extending along the chymiferous tubes ; c", opening leading into the chymiferous tubes from 

 the digestive cavity, o ; g, g, genital organs ; g', fatty globules at base of proboscis. 



Fig. 309. Actinostome of Gemmaria, enlarged. 



Fig. 310. Cluster of lasso-cells of the marginal tentacles. 

 NO. II. 24 



