176 LITIOPA. 



this genus differ from Modiola, not only in the cylindrical form, 

 but also in the circumstance from which the generic name is 

 derived, i. e. of their living in stones. Thus, while the form and 

 structure of the shell bring it near the Mytili or Muscle shells, 

 the habits of the animal cause it to approach the Lithophagi, or 

 rock-eating molluscs of Lamarck. L. Dactylus (fig. 161,) is the 

 Mytilus Lithophagus of ancient authors. 



LITHOLEPAS. Bl. (Ai0oe, Mthos, stone, XeTrag, lepas, rock.) De 

 Blainville's name for Lithotrya, Sow. 



LITHOPHAGIDiE. Lam. (Aidog, lithos, stone ; <£ayw, phaga, 

 eat or gnaw.) A family of the Conchifera Dimyaria, Lam. 

 consisting of terebrating bivalves, gaping anteriorly, having no 

 accessary valves ; and containing the genera Saxicava, Petricola, 

 Venerupis, to which are added other genera enumerated in 

 explanation of figures 91 to 97. Notwithstanding the numerous 

 genera which have been created, I think that the most convenient 

 arrangement will be to reduce them to two, thus — 



1. Petricola, with distinct cardinal teeth, including, Clothe, 

 Venerirupis and Coralliophaga. Fig. 91, 92, 97. 



2. Saxicava, without teeth, including Biapholius, Hiatella, 

 Sphaenia, Byssomya, and Thracia. Fig. 93 to 96. 



LITHOTRYA. G. B. Sowerby. (AiOoq, lithos, stone ; rpvw, truo, 

 to bore through.) Fam. Pedunculated Cirripedes, Lam. — Descr. 

 Eight unequal valves, forming a laterally compressed cone, the 

 lower central valves being very minute ; pedicle fleshy, scaly at 

 the upper extremity ; fixed at the base in a patelliform shelly 

 support. — Obs. This genus derives its name from the power 

 possessed by the animal of making dwelling holes in stones or 

 pieces of rock. The remarkable shelly cups at the base of the 

 pedicle is regarded as analogous to the shelly base of the Balanus, 

 so that this genus would form an intermediate link between the 

 Sessile and Pedunculated Cirripedes of Lamarcjs:. Fig. 39, L. 

 dorsalis. West India Islands. 



LITIOPA. Ran*- Fam. Turbinacea, Lam. — Descr. "Shell not 

 very thick, horny, with a slight epidermis, rather transparent, 



