General History of the Marine Polyzoa. 91 



on tlie characters of the avicularia in the constitution of the 

 family group *. 



The present species has been identified with the M. angu- 

 Josa of Reuss, and this as the earlier name has been adopted 

 instead of Busk's. I have not Reuss's work at hand as I 

 write, and cannot therefore compare his figure with that of 

 Busk. But the species has been figured by Manzoni in his 

 ' Bryozoi fossili Italiani,' and he specially notes the con- 

 stancy of shape exhibited by the opesia (" la bocca," as he 

 calls it), which he describes as always maintaining the 

 characteristic campanulate or horseshoe form, as shown in the 

 figures of Reuss and in his own. Now the opesia of Onycho- 

 cella antiqua is distinctly trifoliate, and markedly so t J it is 

 much larger in proportion to the size of the aperture than in 

 angulosa, placed at the very top of it, and occupying entirely 

 (in my specimens) rather more than half of it. It is arched 

 above and constricted a little above the lower margin by two 

 prominent denticular projections, which form a kind of loop 

 in each corner. The lower margin is raised towards the 

 middle and slightly everted. Of the aviculariura of course we 

 can know but little in the fossil ; but the differences in an 

 important element of structure which I have pointed out may 

 justify, I think, the retention of a separate name for each of 

 the forms. For the present I shall record the recent species 

 as Onychocella antiqua^ Busk (sp.). 



Jullien has formed a genus — Smittipora — of which he 

 makes Vincularia ahyssicola^ Smitt, the type. But, in point 

 of fact, there are no differences of any significance between 

 this species and Onychocella antiqua. The chief distinctive 

 point seems to be that in the latter the tall, slender, chitiuous 

 rod with triangular base which constitutes the mandible has a 

 membranous expansion along one side of it only, while the 

 former has it on both sides. This, with a slight variation in 

 the surface of the cryptocyst, is the basis of the genus. The 

 genus Smittipora is surely needless. 



Ibid. (p. 20 Sep.). 

 Memhranipora mamillaris^ Lamx. \ 



I am now inclined to think that I had not conclusive 

 grounds for identifying the species described under this name 



* " Critical Notes on the Polyzoa," Ann. & Mag. Nat. Hist, for Feb- 

 ruary 1887. 



t Occasionally it is siibtrifoliate, but the typical form is not lost. 



X Histoire d. Puly piers Coralliyeues Flexibles (ICnylish trausL), pi. i. 

 lis. 6. 



