52 PEOCEEDINGS OF THE IsTATIONAL MUSEUM vol. 72- 



is due to the drying up of the ectocyst and has little connection with 

 the true form of the cryptocyst, for the zooecia without ectocyst 

 have a simple salient mural rim often enlarged into facettes when 

 the cryptocyst is deep. Moreover, the latter have very distinct and 

 often deep opesiular indentations. It is likely that Figure 60 of Smitt 

 corresponds to our VelumeUa americana but it has been distinctly 

 picked out by Jullien as the type of his genus Smittipora, although 

 unfortunately none of the Cretaceous species which he classes in the 

 genus have either opesiular indentations or onychocellaria. We have 

 made the same observations on our VelumeUa pJiilippinensis, new 

 species. A dried ectocyst with facettes covers a cryptocyst with 

 opesiular indentations surrounded by a rather regular mural rim and 

 without corresponding facettes. 



The genus Smittipora is therefore not established on sufficient 

 characters since it is the manifest result of an error of interpretation 

 of Smitt 's Figure 60. 



If Jullien had read closely Smitt's text, he would have understood 

 that this figure represented only the zooecia v/ith ectocyst and did 

 not reveal the form of the opesium. Logically, it is necessary then to 

 exclude the genus Smittipora from the nomenclature. 



Since Figure 60 is incomplete and appears to represent another 

 species, Figure 61 remains then the only representative of Vincularia 

 abyssicola. The structure revealed by Smitt's drawing, in perfect 

 accord with our photographs, is that which we have indicated in our 

 genus Redonychocella. There are no opesiular indentations to the 

 cryptocyst; the opesium is elliptical or subelliptical ; the opesiular 

 muscles are placed very high, a little below the hinge of the opercular 

 valve. The onychocellaria are very variable in form and size but 

 they always have the same structure; they are small in Vincularia 

 abyssicola, they are equal to the zooecia, and elliptical in RectonycJio- 

 cella solida (genotype), and they are narrow and lanceolated in our 

 specimens from the American Jacksonian. 



The genus RectonycJioceUa corresponds to the genus Ogivalia Jullien, 

 1881, but with bimembranous onychocellaria. 



Our classification of 1922 is correct except that it is necessary to 

 suppress the genus Diplopholos and place its species in VelumeUa. 

 The zooecial dimorphism on which it was established is only appar- 

 ent and results simply from the great irregularity of the opesium, a 

 frequent and ordinary phenomenon in all the Onychocellidae. The 

 following table gives a summary of our classification: 



Onychocellaria falciform: 



Opesiular indentations nonsymmetdcal Onychocella. 



No opesiular indentations Ogivalia. 



Onychocellaria bimembranous: 



Opesiular indentations symmetrical VelumeUa. 



No opesiular indentations Rectonychocella. 



