498 MR. JAMES RITCHIE ON HYDROIDS [May 28, 



all along the walls, pushing the endoderm inwards until it pro- 

 trudes into the hollow of the gonophore. The male gonophores 

 are similar in origin and shape to the female, but are in general 

 considerably longer. In no case could a spadix be distinguished. 



The structure of the gonophore above described is of the 

 simplest type. It appeai-s to be merely a blind branch of the 

 general coenosarc of the colony within the walls of which ova 

 develop. 



Associated with the specimens were several ci-eeping Hydroids, 

 Filellutn serpens^ Gtispidellci htoviilis, Campanidaria mutahilis, and 

 an endoproctan polyzoon {Glionella ?). 



Localities, (a) St. Vincent, Cape Verde Islands : growing 

 on the bottom of a lighter, 20th and 30th July, 1904.— 

 (6) Dredged ; Boa Vista, Cape Verde Islands, August ? 1904. 



Family Bougainvilliid^. 



Hydractinia VERDI, sp. n. (Plate XXIII. figs. 6 & 7.) 

 Among dredgings taken at Porto Grande four Fusits-like gas- 

 teropod shells wei'e obtained overspread by Hydractinia colonies. 

 The nutritive hydranths, which grow in the grooves of the shell- 

 sculpture, are in various stages of contraction, the longest 5 mm., 

 the shortest with their ring of tentacles almost resting on the 

 surface of the shell. The tentacles are short, set in two almost 

 indistinguishable whorls, and vary in number from 9 to 12, 

 9 being perhaps most frequent. The hypostome is club-shaped. 

 No spiral filaments are present, although along the margin of the 

 shell there occur elongated polyps with insignificant tentacles. 

 Short chitinous spines, about 0-3 mm. long, with jagged edges, 

 occur throughout the colony, being arranged for the most part 

 upon the ridges of the shell. The blastostyles are somewhat 

 smaller than the nutritive hydranths, being about 1 mm. in height, 

 but unlike those of H. echinata they bear well-developed tentacles 

 eight or nine in number. The basal rhizom expansion is thin. 



^Gonosome. — The reproductive bodies are fixed gonophores 

 arising from the body of the blastostyle some distance below the 

 tentacles. They occur in a single whorl containing three or four 

 individuals and ai'e borne on short peduncles. In the specimens 

 examined the gonophores were all female, containing three large 

 ova ; while in the more mature examples these were separated 

 towards the exterior by pigmented bands running from the base 

 towards the summit of the gonophore — branches of the spadix. 



This species is closely related to H. iDaciUca described fi-om 

 Calbuco by Hartlaub (1905, p. 519), but that species difiers in 

 possessing about 15 tentacles on the nutritive hydranths, only 

 5 or 6 on the blastostyles; in lacking spines on the basal expan- 

 sion ; in bearing only one ovum in each gonophore. 



Locality. Porto Grande, St. Vincent, Cape Verde Islands; 10 

 fathoms. 



