Mr. G. B. Sowerby on Pentatrematites. 89 



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

 G. B. Sowerby, F.Z.S., <5fc. 



In oflPering the following descriptions of some hitherto imdescribed 

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

 ledgements to Mr. Gilbertson, of Preston, who has been so obliging 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, obtus^ pentagonalis, infra paululum latior. Scapuhres 

 maximae, elongatae, fer^ ad centrum supem^ attingentes, emargina- 

 tionis interscapularis angulo obtusissimo. Inter-scapulares minimge. 

 Ambulacra linearia, ad basin prominentia. 



This species is nearly 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 extremity. 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 an^le 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-scapulars, " 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 Pentatrematitef. 



