150 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Apr. 6, 



Found in the lower division of the Lower Silurian formation at, the 

 Porto de Louza, in the Serra de^BussacOj 



Named in honour of Don J. Ezquerra del Bayo, of Madrid. 

 Plate IX. fig. 7. a. Exterior, h. Interior. 



NUCULA ESCHWEGII, n. s. Pl. IX. fig. 10. 



N. testa ovata, antice sub lunbonibus excavata, Iseviuscula ; dentibus cai-di- 

 nalibus parvis numerosis. 



Shell ovate, with a depression in front below the beaks ; nearly 

 smooth, with a few inconspicuous lines of growth : hinge-teeth 

 small. 



Length y^, breadth ^ of an inch. 



Found in the lower division of the Lower Silurian formation in the 

 Serra de Bussaco. 



The hinge-teeth have not been clearly seen; they are numerous 

 on the posterior, and few on the anterior side. 



I name this species after Baron Eschwege, one of the earliest 

 writers on the geology of Portugal. 



Plate IX. fig. 10. a. Exterior, h. Interior. 



NucuLA Maestri, n. s. Pl. IX. fig. 9. 

 N. testa subrotunda, subseqiiilaterali, Iseviuscula, lineis concentricis paucis. 



Shell slightly angular at the beaks, otherwise nearly round, marked 

 with three or four impressed concentric lines ; beaks nearly medial : 

 hinge-teeth small and numerous. 



A clumsy, inelegant shell ; the teeth have not been well seen. 



Diameter \ of an inch. 



Found in the lower division of the Lower Sjhirian formation at the 

 Portela de Loredo, in the Serra de Bussaco. 



Named after Don Amalio Maestre of Madrid. 



Plate IX. fig. 9. a. Exterior, h. Hinge-teeth. 



NucuLA Beirensis, n. s. Pl. IX. figs. 11 & 12. 



N. testa subglobosa, umboiiibus prominulis, laeviuscula, lineis paucis con- 

 centricis : cardine arcuate, dentibus anticis 3 majoribus, posticis 20 sub- 

 sequalibus : lamella interiori museulum anticum limitante. 



Shell subglobose with projecting slightly anterior beaks, marked 

 with a few concentric lines : hinge arched, with three strong anterior 

 teeth separated by an interval from about twenty smaller equal pos- 

 terior teeth : anterior muscular impression deep, and bounded on its 

 inner side by a strong plate. 



Diameter \ of an inch. aoiio'.) 



Found in the lower division of the Lower Silurian formatioii'^t**" 

 Riba de Baixo, in the_&erra de^usgaco. '^^ 



This species and the following one, N. Bussacensis, are distin- 

 guished from the usual forms of Nucula by having a strong internal 

 plate bounding the anterior muscle on its imier side, similar to the 

 internal plate of Cucullcea glabra, &c., and to that of the genus 

 Redonia : as in other respects they appear to agree with Nucula, 



