2i8 Papers from the Marine Biological Laboratory at Tortugas. 



CTENOSTOMATA. 

 Genus Bowerbankia Farre, 1837. 

 Bowerbankia gracilis Leidy. 



Leidy, 1855, p. 142, — HiNCKS, 1877, p. 215 (Valkeria caudata); 1880, p. 521 (Bower- 

 bankia caudata). — Verrill and Smith, 1873, P- yog {Vesicularia gracilis), 

 and p. 710 (F. fusca). — Verrill, 1880, p. 28 {Vesicularia gracilis). — Lev- 

 INSEN, 1894, p. 82 {Bowerbankia caudata). — Osburn, 1912, pp. 253-245 

 (synonymy); 1912a, p. 287. 



Specimens of this species, which do not seem to differ from Woods Hole 

 material, were taken in the moat at Fort Jefferson and on the piles of the 

 docks, attached to shells, or creeping over the sea-weed, and covered to such 

 an extent by coral mud as to almost obscure them. No erect branches 

 were noted. Many individuals show the caudate process of the variety 

 caudata (Hincks). 



On the North American coast the species has been identified by the 

 writer from Nova Scotia, Maine, Massachusetts, Connecticut, New Jersey, 

 North Carolina, and Florida. Otherwise it is known from England and 

 Denmark. 



It is quite probable that the genus Bowerbankia, as Waters (1910, pp. 

 241 and 244) suggests, must be fused with Zoobotryon, but as Waters himself 

 keeps them separate pending more thorough studies of the ctenostomes, 

 the writer has not the temerity to combine them. The only marked dis- 

 tinguishing characters are the much greater softness and hyalinity of the 

 stock and the absence of a creeping stolon in Zoobotryon. These characters 

 will readily separate the one species of Zoobotryon from any Bowerbankia 

 with which the writer is acquainted. 



Genus Zoobotryon Ehrenberg, 1831. 

 Zoobotryon pellucidum Ehrenberg. 



Ehrenberg, 1831, pi. m, fig. 10. — Sonder in Coll. Binder {Ascothamnion trinitatis). — 

 Waters, 1910, p. 243. 



This species, first described from the Mediterranean, is common at the 

 Tortugas, floating and attached, especially in the Fort Jefferson moat and 

 about the piles of the dock. One colony 8 inches across was observed. The 

 zooecia in all cases were much obscured by a layer of white coral mud 

 adhering to the ectocyst. 



Not previously recorded for the Florida region. Sonder (see above) 

 recorded it as a plant from the island of Trinidad, and according to Waters 

 (see above) it is known from the Isle of Pines, South Australia, Zanzibar, 

 the Red Sea, and the Cape Verde Islands. 



Genus Cylindrcecium Hincks, 1880. 



Cylindroecium giganteum (Busk). 



Busk, 1856, p. 93 {Farrella gigantea). — Hincks, 1880, p. 535. 

 This species, which has been recorded from the British Isles, from various 

 localities in the Mediterranean Sea, from the Red Sea, and from the Queen 



