84 CEETACEOUS PELEOYPODA 



figs. 1-4). Prof. King strongly advocates the idea that Anthracosia is a genus of the 

 JJnionid^^ but there can be little doubt as to its close relation to Notontya, and it 

 is even very difficult to distinguish between some of the species generically. 

 The ligamental area of Anthracosia much more recalls that of Fanopwa and Cyrto- 

 daria, than that of any known TJnionidm\ and as Salter distinctly asserts that it is 

 a marine or brackish water shell, I think its classification in this place may be the 

 more correct one. The name Anthracosia has as yet been restricted to palaeozoic 

 species only. 



3. Quenstedtia, Morris and Lycett, 1853, (Moll. Great OoL, pt. II, p. 96). 

 Shell oblong, equivalve, moderately solid, inequilateral, umbones nearly contiguous, 

 hinge with a transverse cardinal tooth in the left and a corresponding pit in the 

 right valve ; ligament external, placed in a long narrow groove, pallial sinus small. 

 Only a few Jurassic species have as yet been referred to this genus ; its systematic 

 position is doubtful ; it is allied to the Saxicavibm by its hinge and to the Anatinid^ 

 by the form of its shell, and it may be considered intermediate between Saxicava and 

 Notomyu in respect of its dentition. 



4. Faramya^ Conrad, 1862 (?). Under this name Conrad introduces into the 

 family Saxicavidje a small shell which he formerly described as Myalina suhovata 

 from the miocene beds of Virginia (see Proc. Acad. Phil., 1862, p. 572). The 

 species which has the general form of a Saxicava or of a Trapezium fOypricardia) 

 is described as possessing a small spoon-shaped, emarginated process in each 

 valve. It is not stated whether it indicates the presence of a cartilage or not ; 

 reference is made to the muscular and pallial impressions, but their form is not 

 described. 



5. Saxicava, El. d. Bellv., 1802.* Shell elongated, rugose, posteriorly gaping, 

 anteriorly nearly perfectly closed, adult specimens have the right valve sometimes 

 larger than the left ; hinge with one tooth (occasionally two) in each valve, becom- 

 ing sometimes obsolete in aged specimens, when the shells usually assume a great 

 thickness ; ligament small, not prominent ; pallial sinus moderate and often indis- 

 tinct ; — usually burrowing in stones and corals. 



The animal has the siphons separated at the end with fringed orifices, but is in 

 other respects very similar to that of Bocellaria, 



With regard to this genus it deserves to be noticed that the hinge-teeth do 

 not in all cases become obsolete with age, as often stated in the generic character 

 of this genus ; several of our eastern species (S. similis and others) have them 

 permanent and perfectly similarly formed to those of Fanopcsa. 



* Agassiz and Herrmansen attach to Hiatella of Daudin 1802 as the date of publication, and this would 

 sufficiently justify the adoption of the name Saxicava in preference to that of Hiatella, simply because the former 

 name has become generally known and has already been introduced in all the larger conchological works. Chenu (Man. 

 II, p. 25,) gives the year 1799 as the date of publication of the name Hiatella, but I have not been able to find the 

 authority for this quotation. Deshayes (Paris foss., 2nd edit., I, p. 167,) gives 1801 as the year in which the name 

 ^*cKi(eZ?« was published, quoting as authority the " r histoire des coquilles" of Bosc, the same as cited by Agassiz 

 and Herrmansen. 



