GEMMARIA CLADOPIIORA. 



185 



but is curved in the opposite direction ; near the upper bend of the 

 chyniiferous tubes, it runs up into a point, making a sharp and deep 

 groove round the projection of the 



Fig. 308. 



FiR. 303. 



spherosonio ; the chyniiferous tubes 

 ((•', 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 little ; 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 

 conti'action of a portion of the walls ; the walls are thick, and open into 

 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. sio. 

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

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

 the tentacles are stretched out very obliquely from the bell, 

 and they often remain perfectly motionless in this po.-;ition ; 

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



Professor Clark discovered at Nahant a Hydroid closely resem])ling 

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

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

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

 Massachusetts Bay, Nahant (A. Agassiz). 



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



? Cat. No. 03, Nahant, May, 1862, II. J. Clark. 

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



Hydrarium. 



Fig. 308. (Quarter of the disk of CI. fla<lopliora, spcn from tlio aliaftlnal jwlc. r, circular 

 tube; c', chymifenius tube; ?;, .<ensitive bulb, liaviu^ a great ac cuniulatiou of ])ignieut auil lasso 

 cells e.xtendiui; almig the ehyinit'erous tubes ; <■", ojjeiiiug leadiug iuto the ehymileruus tidies from 

 the iligestlvct cavity, o : </, ij, genital organs ; r/', fatty globules at ba.se of jiroboseis. 



Fig. 309. Actinostomi^ of Gemmaria, enlarged. 



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

 NO. II. 24 



