452 On the Presence of Ossa transversa in a Ghelonian. 



dition, and from the prevalent opinions as to the value of the 

 three reagents employed we must unanimously declare against 

 the spirit-specimen and the intercellular spaces. Others also 

 appear to have made similar observations. In a recent 

 French memoir upon the histology of the Lamellibranchs * 

 we find the epithelium everywhere represented as closed, only 

 one figure shows, exactly like my spirit-specimen of Tridacna, 

 the epithelium traversed by numerous " intercellular spaces." 



LXII. — Oji the Presence of Ossa transversa in a Cheloman, 

 By G. A. BoULExVGER. 



The object of this note is to record the presence of transverse 

 bones in the skull of Hydraspis Hilairii, Schw. The absence 

 of that element had hitherto been regarded as characteristic 

 of the order Chelonia. 



Lower view of anterior part of skull. 



As may be seen from the above figure, the bone {tr.) is 

 intercalated between the pterygoid, the palatine, the maxillary, 

 and the jugal; it is suturally united with the latter only 

 anteriorly and posteriorly, its outer border being free. 



• L. Eoule, " Eecherclies histologiques sur les Molliisques laraelli- 

 brauches," in Journ. Auat. et Physiol, tome xxiii, (1887), p. 31. The 

 figure referred to is pi. v. fig. 8, 



