Mr. G. B. Sowerby on Pentatrematites. 89 



Art. IX. On some new species of Pentatrematites^. By 

 G. B. Sowerby, F.L.S,, &;c. 



In offering the foUawing descriptions of some hitherto undescribed 

 Pentatrematites I beg in the first place to present my grateful acknow- 

 ledgements to Mr. Gilbertson, of Preston, who has been so obhging as to 

 communicate them together with some observations, which I take the 

 liberty of transcribing ; and then to express a hope, that the brief detail 

 concerning them which I am enabled to give may not prove entirely use- 

 less in the cause of Science. 



Spec. 6. Pentatrematites angulata. 



P. subglobosa, obtuse pentagonalis, infra paululum latior. Scapulares 

 maximse, elongatae, fere ad centrum supern^ attingentes, emargina- 

 tionis interscapularis angulo obtusissimo. Inter-scapulares minimae. 

 Ambulacra Hnearia, ad basin prominentia. 



This species is neai'ly globose, but it is rendered obtusely pentagonal 

 by the prominence of the ambulacra, and it is a little wider at the lower 

 than at the upper extremitj^ The pelvis is not sufficiently preserved, in 

 the only two specimens I have seen, for me to describe its particular form. 

 The scapulars are very large, much elongated, reaching nearly to the 

 centre at the upper end, where the angle formed by their junction with 

 the inter-scapulars is very obtuse. The inter-scapulars are very small, 

 ambulacra linear, prominent at their bases. 



This species may be easily distinguished from the P. Derbicnsis by the 

 size of the inter-scapiilars, " the division of the second row of plates (inter- 

 " scapulars) being" according to Mr. Gilbertson, " very near the apex, 



* The appellation by which Say has designated this genus is here, for rea- 

 sons which will be obvious to the classical student, changed from Pentremites 

 to Pentatrematites. 



