MAZATLA UNIVALVES 



p. 181, but Hinds points out differences, TJies. Conch, p. 184. 

 Long. "5, long. spir. '32, lat. '16, div. 30. 

 Hob. Acapulco, Sonsonati ; Mus. Cuming. Xipixapi, Gum- 

 ing. Mazatlan ,- extemely rare ; L'pool Col. 



Tablet 1878 contains 1 specimen, presented by E. D. Darbi- 

 ehire, Esq. 



FAMILY PLETJKOTOMIDJE. 



All the young Pleurotomidae examined have the apex normal, 

 with about three whirls smooth and subtransparent. The 

 opercula in this Suborder, as in Proboscidifera, are very fre- 

 quently repaired after fracture.* Whatever be their normal 

 condition, they always reconstruct from a central nucleus : a 

 circumstance which seems to shew that the variations in oper- 

 cula are not of so much importance as in the shells ; the latter 

 being almost always repaired after the normal pattern. 



GENUS PLEUBOTOMA, Lam. 



Jburn. Hist. Nat. 1799, pars : canal elongated, operculum 

 subtriangular, nucleus at the anterior extremity. 



Turris, '(Humph.) Gray, Proc. ZooL Soc. 1847, p. 134.- 

 H. $ Ad. Gen. vol. i. p. 87. (Non Montf.) 



-f- 457. PLEUROTOMA FUNICULATA, Vol. 



Kien. Icon. Conch, p. 24, no. 18, pi. 16, f. l.Rve. Conch. Ic. 



pi. 11, sp. 95. 

 =P. olivacea, var. five. loc. cit. (a prim, man.) pi. 4, sp. 27 ; 



non Sow. Proc. Zool. Soc. 1833, p. 136. 

 Surcula (Turris) funiculata, H. fy A. Ad. Gen. i. 88. 



The aspect of the Mazatlan shells is intermediate between 

 the figures of Kien. and Itve. They differ from the figure of 

 P. olivacea in the widely excavated space of the posterior sinus, 

 and in the keeling of the whirls below it. The epidermis in 

 the young shells is ashy, in the adult of a rich glossy olive. 

 There are numerous coarse spiral striae, two of which appear 

 above the suture. There are about 10 nearly obsolete costae, 

 rising into tubercles at the periphery. iNuclear whirls smooth. 



* V, Gray on Reproduction of Opercula, Ann. Nat. Hist. 1851, p. 419. 



