1853.] RIBEIRO AND SHARPE — BUSSACO. 151 



they are left in that genus. Neither in these nor any of the species 

 of Nucula described in this paper can we detect the internal liga- 

 mental pit ; but as all the specimens are mere casts, it is impossible 

 to say that it has not existed in them. 



Plate IX. fig. 1 1 . Internal cast. 



Fig. 12. Internal cast of another specimen. 



Nucula Bussacensis, n. s. Pl. IX. figs. 13 & 14. 



N. testa transversim ovata ; Uneis inconspicuis concentricis : cardine sub- 

 arcuato, dentibus 4 anticis, 12-15 posticis : lamella interiore, musculum 

 anticum limitante. 



Shell transversely ovate with a slight anterior depression below 

 the beaks, marked with some faint concentric lines : hinge curved, 

 with four anterior and twelve to fifteen posterior teeth : anterior 

 muscular impression deep, and bounded on its inner side by a strong 

 plate. 



Length ■§, breadth f of an inch. 



From the lower chyisipn of __the Lower_Silu^ of the 



Serra de Bussaco. 



Plate IX. Hg. 13. Internal cast. 



Fig. 14. a & b. Exterior and internal cast of another imperfect 

 specimen. 



Leda Escosur^, n. s. Pl. IX. fig, 8. 



L. testa transversim elongata, Iseviuscula, antice rotundata, postice rostrata : 

 urabonibus prominulis : cardine recto, dentibus numerosis, continuis, 

 inaequalibus. 



Shell transversely elongated, with projecting beaks : anterior end 

 rounded, posterior produced into a long beak : hinge straight, with 

 a continuous row of very numerous small teeth. 



Length ^, breadth ^ of an inch. 



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

 Portela de Loredo, in the. Serra-de Bussaco. 



In the specimen figured, the end of the posterior side is incomplete. 



Named after Don Luis de la Escosura. 



Plate IX. fig. 8. a. Exterior, b. Internal cast. 



DoLABRA? Lusitanica, u. s. Pl. IX. fig. 3. 



D. ? testa transversim ovato-rhomboidea, concentrice lineata, antice rotun- 

 data, postice subangulata : cardine recto, dentibus anticis 2 vel 3 ?, 

 postica unica, elongata, crenulata. 



Shell transversely ovato-rhomboidal, covered with unequally raised, 

 concentric lines ; anterior end broad and rounded, posterior side 

 sloping with an obscure rounded ridge extending from the beak to 

 the posterior extremity. Hinge with two or three ? strong anterior 

 teeth and a long posterior plate parallel to the hinge-line, which is 

 crossed by numerous small teeth or crenulations. 



Length |, breadth jL of an inch. 



Common in the lower division of_.the Law.er.SiljiriaiiXQraaation of 

 the Serra de Bussaco. 



