Rev. T. Hincks on a new Genus of Hydroida. 421 



LIV. — On Ophiodes, a neiv Genus 0/ Hydroida. 

 By the Rev. Thomas Hincks, B.A. 



[Plate XIV.] 



While dredging this autumn in Swanage Bay, on the coast of 

 Dorset, I have obtained a new Sertularian Hydroid, which offers 

 some very interesting pecuHarities. Of these the most remark- 

 able is the presence of an organ which takes the place of the 

 nematophore, but is unique in appearance and structure. The 

 polypite, too, differs in form from that of any other Hydroid 

 with which I am acquainted, and is furnished with webbed ten- 

 tacles — a character which has only been noticed hitherto among 

 the Campanularida. 



This very curious Zoophyte must be refen-ed to a new genus, 

 to which I shall assign the name Ophiodes. It may be thus 

 characterized : — 



Subkingdom CCELENTERATJ. 



Class HYDROZOA. 



Order HYDROIDA. 



Suborder SERTULARIDA. 



Family Halecidse. 



Ophiodes*, nov. gen. 



Hydrocaulus simple or branched, rooted by a creeping stolon. 

 Hydrothec(B vase- shaped, terminal ; polypites not retractile within 

 the calycle ; the body deeply constricted a little below the base 

 of the tentacles; tentacles in a single verticil, muricate, webbed 

 for about a quarter of their length, and surrounding a conical 

 proboscis ; tentaculoid organs borne singly on the hydrocaulus 

 (near the calycles) and on the stolon, highly extensile, protected 

 at the base by a small chitinous cup, and terminated at the 

 upper extremity by an enlarged capitulum, armed with thread- 

 cells. Reproduction unknown. 



The remarkable tentacular organ with which the Ophiodes is 

 furnished, and which may be regarded as the equivalent of the 

 nematophore, consists of a very extensile, snake-like appendage, 

 with an enlarged head, attached at the lower extremity by an 

 extension of the coenosarc. The base is protected by a small 

 chitinous tube, which expands from its point of origin upwards, 

 and answers to the theca of the ordinary nematophore. The 

 capitulum contains numerous thread-cells, from which a barbed 

 sheath and a very long thread are emitted. 



* Der. o^KDS^f, snake-bearer. 



