94 CATALOGUE OF 



Jenyns, who introduced a superfluous " i " into the specific name, 

 gave a fuller diagnosis (83, p. 308), which is here reproduced: 



" Testa oblique ovalis, vontricosn, antice planiuscula, dis- 

 tincte inaequilateralis, tenuiter striata, nitide lutescenti-alba, 

 vel cornea, saepius partim praBcipue ad apicem, sorde ferrugine<a 

 obtecta : umbones acutiusctili, projectura parva laraelliformi 

 adorn atis. 



Obs. In pullis projectura raedio valvularum insidet ; hinc 

 gradatim assurgit, accrescente testa/' 



To this it is now necessary to add the details concerning the 

 hinge characters : 



Hinge (PI. II, f. 4 ; III, f. 9) about | the length of the shell, 

 not very strong, fairly wide, projecting well inwards, gently 

 curved. 



11. V. a. i. long, nearly \ the length of the hinge-line, narrow and 

 straight; base strong, slightly swollen; apex central, 

 scarcely prominent, pointed -obtuse; ridges rounded, 

 about equally steep, the umbonal descending a little 

 the lower. 



a. ///; about 3 the length of a. /., narrow, somewhat apposed 

 to the shell-margin ; apex near distal end, obtuse- 

 pointed ; ridges slightly rounded, distal short and 

 steep, umbonal long and gradual, tending to coalesce 

 towards the umbo with that of a. i. 



3. prominent, narrow, arcuate ; a thin, sharp, parallel to 

 shell-margin ; b thickening and curving down to the 

 inner margin of the hinge-plate, sulcate. 



p. i. about 3 the length of the hinge-line, narrow, fairly 

 straight; base strong and swollen; apex central, 

 scarcely prominent, extremely obtuse ; ridges round- 

 edged, sloping about equally and fairly gradually. 

 p. in. about | the length of p. /., slight, narrow, straight, 

 distinct ; apex distal side of centre, prominent ; ridges 

 fairly sharp, umbonal gradually, distal steeply sloping. 

 L.V. a. II. nearly | the length of the hinge-line, narrow, straight ; 

 base strong, slightly swollen; apex central, prominent, 

 round - pointed ; ridges rounded, descending about 

 equally, steeply at first then more gradually. 

 2. prominent, obtusely triangular, apex backwardly 

 directed^ base continuous with that of a. //. 



4. thin lanlelliform, slightly arcuate, curving round 2 

 from a point near the shell-margin anterior to the 

 umbo to half-way across the hinge-plate on the 

 posterior side. 



p. II. about 3 the length of the hinge-line, narrow, curving 

 with the shell-margin ; base strong and straight ; apex 



