CORYMORPHA. 387 



CORYMOEPHA, Sars (in part). 



Name. — From Kopm-i), a club, and lio^ipi], lonii, in allusion to the form of the hydranth with 

 its stem. 



TROPHOSOME. — Hydrocaulus emitting towards its proximal extremity tubular 

 fleshy processes ; perisahc replaced by a delicate filmy pellicle. Hydraxths flask- 

 shaped, abruptly distinct from the hydrocaulus ; proximal tentacles imperfectly 

 contractile, larger than the distal, and arranged in a single verticil near the base of 

 the hydranth, the distal tentacles very contractile, forming several closely approxi- 

 mate alternating verticils round the base of a conical hypostome. 



GONOSOME. — -Plaxoblasts borne on branched peduncles which spring from the 

 body of the hydranth between the proximal and distal sets of tentacles, with a deep- 

 belled umbreUa, a well-developed simple-mouthed manubrium, and a single marginal 

 tentacle ; each of the radiating canals terminates at its junction with the circular 

 canal in a bulbous expansion without distinct ocellus ; one of these bulbs is larger 

 than the other, and from this alone the solitary tentacle is developed. 



The genus Cori/inorjiha was instituted by Sars for the Cori/morj)ha nutans, a beautiful 

 hydroid discovered by the celebrated Scandinavian zoologist on the coast of Norway. Since 

 then several species have been admitted into the genus, but I believe that of these one only has 

 any claim to be oongenerically associated with the original Cori/morpha nutans. 



Among the characters which especially strike us in the planoblast of Corymorplta is the 

 absence of symmetry, as shown in the development of only a single marginal tentacle. This 

 must not be confounded with that deficiency of marginal appendages which in other planoblasts 

 is merely the result of an immature condition. Here it is a permanent feature, having an im- 

 portant morphological significance, and undoubtedly entitled to a place among the essential 

 characters of the genus. 



