356 MAZATLAN UNIVALVES 



407. ?IsAPis , sp. ind. 



Tablet 1703 contains a fragment of a species resembling 

 I. ovoidea, but with very numrrous fine spiral ribs, with broad 

 concave interstices, crossed by transverse ridges most develop- 

 ed on the penultimate whirl, 



Hob. Mazatlan : 1 sp. on Spondylus ; If pool Col. 



FAMILY EISSOIDJE. 



GENUS EISSOESTA, D'Orb. 



Voy. Am. Her. 1840, p. 395. Phil. Handb. Conch, p. 172.= 

 H, fy A. Ad. Gen. vol. i. p. 327. Base slightly channeled, 

 labrum thickened, operculum neritoid. 



Eissoa, pars, auct. 



408. EISSOINA STRICTA, Mke. 



R. t. alba, subturritd, solidd, anfractibus ?x., apice ? ; 



labro incrassato, ad mediam partem producto ; labio parvo, 

 reflexo ; columelld truncata ; costis radiantibus subrotundatis, 

 in anfractu utroque circiter xx., striulis spiralibus obsoletis ; 

 suturd impressd, costis ad apicem continuis. 



Eissoa stricta, Mice, in Zeit.f. Mai. 1850, p. 177, no. 37. 

 Comp. Eissoa fortis, C. B.Ad. Pan. Shells, pp. 178, 314, no. 245. 

 Comp. Eissoina pyramidata, A. Ad. 



A single specimen of this shell was found by Mr. Hanley in 

 the Spondylus washings. Menke's shell is still larger, measur- 

 ing 3 '7 byl* lines. Even Mr. Hanley's specimen is very 

 much larger than E. Woodwardii, which in general form it 

 much resembles, measuring long. '27, long. spit:, (apice carente) 

 17, lat. '11,6^.20. 



Sab. Mazatlan ; extremely rare ; Havre Col. 



Tablet 1704 contains some fragments which seem to belong 

 to this species, with an apex resembling that of E. Woodwardii, 

 but larger in proportion ; and a sketch of the unique shell in 

 Mr. Hartley's Collection. 



