262 G. BUSK. 



direction parallel with the longitudinal axis of the stem. 

 These fibres^ in many^ if not in most, of which an elongated 

 nucleus may be perceived at about the middle of its length, 

 are attached at either end by a slight expansion. Here and 

 there one may be perceived bifurcated, but for the most part 

 they are undivided. In general character they bear so close 

 a resemblance to one form of involuntary muscular tissue 

 that it can scarcely, perhaps, be doubted that they are con- 

 tractile in function, and, consequently, that by their agency 

 the Clavopora is capable to bending its stem in various 

 directions. 



The club-shaped upper extremity, as well as can be made 

 out in the spirit specimen, consists of cells similar to those of 

 which the peduncle is constituted, and containing like them the 

 same peculiar contractile fibres. The cells, however, in this 

 portion of the polyzoary are more expanded, and in several 

 of them (fig. 3 a) may be distinctly perceived the body of a 

 polypide in the contracted condition, and proceeding from 

 it elongated, slender, nucleated fibres, representing the 

 retractor muscles. I have been unable to determine with 

 any certainty the number of tentacles with which the poly- 

 pide is furnished, but should estimate it at from twelve to 

 fourteen. The outer wall of the cellular space or zoooecium 

 presents an infundibuliform depression, marking the point at 

 which the polypide was protruded. 



From the characters above given I have little hesitation in 

 referring the genus to the family of the Haley onellece, with 

 the following diagnosis : 



Class. POLYZOA. 



Order. — Ctenostomata. 

 Fam. — Haley onelle<e. 



Gen. — Clavopora, Bk. 



Zoarium, simple claviform, subcapitulate, composed of 

 distinct cells, traversed by nucleated (probably contractile) 

 fibres. 



Sp. — C. Hystricis. The only species. 



Hab. — Mediterranean ; Carpenter. 



