7*0 Mr. G. B. Sowerby on Ilinnites. 



nearly straight. When young the shell is perfectly regular, but 

 it generally becomes irregular by moulding itself close to the sub- 

 stance to which it is fixed, as it increases in size. 



I shall now proceed to give the characters of the five congeneric 

 species which are at present known. 



1. HinnUes Coriesi/i^ Defr. Diet, des Sciences Nat. torn. 21 

 p. 169. 



Testa crassiuscula, oblonga, valva inferiore conceutrice fim- 

 briata, valva superiore longitudinaliter radiato-muricata, spinis 

 breviusculis linguliformibus ; long. max. 5 poll.* 



Shell not very thick, oblong ; lower valve covered with fringes 

 disposed in concentric circles ; upper valve covered with short 

 linguliform spines disposed in longitudinal rays, length (height, 

 according to Mr. Gray) 5 inches. 



This shell in its young state is very smooth, and in a slight de- 

 gree radiately striated. It is only found in a fossil state, in the 

 vicinity of Piacenza. 



2. Hinnites Dabuissoni. Defr. loc. cit. p. 170. 



Testa oblonga, valva inferiore concentrice striata, valva supe- 

 riore longitudinaliter confertim radiata, radiis prope marginem 

 imbricatis ; long. max. 4 poll. 



Shell oblong, lower valve covered with concentric circles, 

 which mark the numerous, period;* of its increase ; upper valve 

 with numerous longitudinal rays, which are imbricated near the 

 margins : length (height, according to Gray) 4 inches. 



Found in a fossil state at St. Paul-trois-Chateaux and La 

 Chevroliere. The muscular impression in this and the last is 

 generally very distinct and large. 



3. Hinnites glganteusA Hinnita gigantea. Gray, in Ann. of 

 Philos. Aug. 1826. Lima gigantea. Id. in loc. cit. 



* I have given the characters of the three first as nearly as I could accord- 

 ing to Defrance and Gray; of the other two I have myself drawn up the 

 characters. 



+ The term giganteus is not correctly applicable to this species, as it is the 

 smallest but one, of five here indicated. Since, however, it hsls been pub- 

 lished under this name, 1 do not consider myself at liberty to alter it. 



