184 Mr. L. Reeve on the History, Synonymy, and 



The grounds for this conclusion appear to me to be very in- 

 sufficient. No loop, it is true, has been observed ; but it is to 

 be remarked that the shell much more resembles that of the 

 free-looped Terebratula than that of the subgenera in which the 

 labial appendages rest more directly on the shell. The most re- 

 markable peculiarity of this shell, as compared with ordinaiy 

 adults, is the prominence of the dorsal umbo. The shell is 

 almost double-beaked. Its internal structure is not yet under- 

 stood. "Woodward and myself,^^ writes Mr. Davidson to me, 

 in a letter just received, " wasted a whole day at the British 

 Museum (Api-il 27th, 1859) in endeavouring to tind some kind 

 of loop in T. capsula, but could find none, and thought it the 

 fry of some other species.'' 



Subgenus 10. Morrisia, Davidson. 



Apophysis a short simple loop attached to a central process in the 

 form of a spur. 



41. Terehratula [Morrisia) anomioides, Scacchi, Philippi, Enum. 

 Moll. Sicil. ii. p. 69, pi. 18. f. 9; Conch. Icon. pi. 10. f. 40. 



Orthis anomioides, Scacchi. 

 Terebratula appressa, Forbes. 

 Morrisia anomioides, Davidson. 



Hab. Mediterranean (dredged in the ^gean from a depth of 

 95 fathoms) ; Forbes. 



An Anomia-like form, in which the ventral valve is very little 

 beaked, and the foramen encroaches upon the dorsal valve, 

 occupying the place of the umbo; there is consequently no 

 deltidium. 



42. Terebratula [Morrisia) Davidsoni, Deslongchamps, Ann. and 

 Mag. Nat. Hist. 1855, xvi. pi. 10. f. 20 a, b, c, d. 



Hab. Mediterranean (dredged at Tunis, adhering to Caryo- 

 phyllia ramea) ; Deslongchamps. 



I do not see that the differences alleged to exist between this 

 species and the preceding are clearly specific. Far greater dif- 

 ferences may be observed in bivalves of snnilar habit of which 

 specimens are more abundant, as of the common Anomia ephip- 

 pium for example, which it so closely resembles externally, though 

 minute and of a different organization. Morrisia Davidsoni is dis- 

 tinguished from M. anomioides, &o far as the few specimens known 

 permit of a distinction being noted, by the following characters: — 

 The shell is larger and of a more transverse growth, with the 

 concentric lines of increase rising almost to the sharpness of 

 asperities. The foramen is large, and encroaches so much upon 

 the dorsal valve as to appear almost to belong to it alone ; and the 



