494 MR. JAMES RITCHIE OX HYDROIDS [May 28, 



showing ill optical section a manubrium suiTounded by a horse- 

 shoe-shaped mass of generative plasma. In only one gonophore 

 of the many examined was there a trace of actinula-formation, 

 tentacles being indicated by apparently about 8 filaments. 



Locality St. A^incent, Cape Yerde Islands. Found on bottom 

 of a lighter, 30th July, 1904. 



Previous record, off Natal coast. 



Family C L A v I D ji. 

 SoLENioPsis *, gen. no v. 



Type. S. dendriformis, sp. n. 



Generic characters. — Trophosome. Colonies branched and 

 fascicled. The branches originate from the division of a cceno- 

 sarcal strand into two portions which lie parallel and close to one 

 another for a considerable distance, each becoming sheathed in a 

 chitinous perisarcal tube, the outermost strand finally bends out- 

 wards and becomes free to form a branch [vide text-fig. 142, p. 496). 

 The hydranth-bearing ramuli originate in the same way as the 

 branches. Hydranths cylindrical, with club-shaped proboscis 

 and many scattered filiform tentacles. 



Gonosome. — The reproductive bodies are permanently fixed 

 gonophores of a simple type. They ai'e blind sacs arising from 

 the coenosarc some distance beneath the hydranth and lying 

 within the perisarcal tube from which the hydranth projects. The 

 ova are developed in the wall of the sac. 



The genus Solenioj^sis is distinguished by its peculiar mode 

 of branching and by its gonophore. The bi-anching, which is 

 more fully described in the discussion on the species, appears to 

 be similar to that of Corydendrium (Weismann, 1883). I have 

 not seen the original description, but Dr. Fowler says with regard 

 to the branching of the genus, " The young buds, instead of 

 breaking through the perisarc and growing outwards as is iisual, 

 grow upwards for some distance inside it and surround themselves 

 with secondary perisarc " (Fowler, 1900, p. 13); and this agrees 

 with the structure in the present genus. Corydendrhiin differs 

 from Soleniopsis, however, in having gonophores which give rise 

 to free medusae (Delage, 1901). 



The gonophores here are of great length and of extremely 

 simple structure. They are also peculiar in lying within, and thus 

 being protected by, the tube which contains the trophosome, 

 instead of bursting through the perisarc and forming hernia-like 

 o-lobular projections like most other gonophores. The ova and 

 spermatozoa apparently escape from the mouth of the tube, 

 passing between the swollen bulb beneath the neck of the hydranth 

 and the perisarcal wall. 



On account of the scattered filiform tentacles on the hydranth 



* The name of tlie genus, Soleniopsis, is intended to suggest the resemblance 

 between the parallel-ljang coenosarcal strands of the colony and the " soleuia " of 

 Alcj'onai-ians. 



