746 CLASS XIT. 



Sp. Petricola roccellaria LAM., DESH. Conchyliol. PL 12, fig. 7, &c. (on the 

 animal of Petricola see PHILIPPI 1. 1. p. 188, Tab. vu. figs, n 14). 

 Fossil species from the tertiary formations are known. 



Saxicava FLEURIAU DE BELLEVUE, LAM. (Hiatella DAUD., 

 LAM., Byssomya Cuv.). Shell with tooth obsolete, tuber culiform, 

 or edentulous. Foot very large, often byssiferous. 



Sp. Saxicava pholadis LAM., Myiilus pholadis L., MUELLEB Zool. Danic. 

 Tab. 87, figs, i 3 (infer.), BLAINV. Malacol. PL 80, fig. 5; Saxicava 

 arctica PHILIPPI, Solen minutus L., LAM., Mya arctica L., Hiatella arctica 

 LAM., Encycl. mefh., Vers. PL 234, fig. 4, BLAINV. Malac. PL 80, fig. 6 

 (named Rhomboldis rugos.}, Cuv. R. Ani., Moll. PL 1 10, fig. i, &c. 



Family XVII. Tellinacea. Mantle with lobes concrete poste- 

 riorly, margin tentaculiferous. Tracheae two, separate, often very 

 long. Foot triangular, compressed. Shell transverse, equivalve, 

 inequilateral, with posterior part often shorter. Ligament external. 

 Two muscular impressions remote. Impression of mantle sinuate 

 posteriorly. 



That margin of the shell which is ordinarily the longest, is here often the 

 shortest, the hindmost, namely, or that where the ligament is situated. It 

 was an error, therefore, in LAMARCK to suppose that in Donax the liga- 

 ment is displaced, and lies on the lunula; it lies, as in all bivalve shells, 

 behind the point. 



Donax L. Shell transverse, posteriorly obtuse, flat. Cardi- 

 nal teeth two either in both valves or in left, a single tooth bipar- 

 tite in right ; lateral tooth single or two lateral teeth, subremote, 

 sometimes obsolete. Ligament short. Animal (Peroncea POLI) 

 with tracheae long, distinct, unequal, the inferior longer ; cirri at the 

 orifice of anal (superior) trachea simple, at the orifice of branchial 

 trachea ramoso-digitate. Foot large, conspicuous. 



Sp. Donax scortum L., D'ARGENVILLE Conchyl. PL 21, fig. L, BLAINV. 

 Malac. PL 71, fig. i, DESHAYES Conchyl. PL 14, figs. 12 15 (Donax 

 pubescens L. variety) ; hab. Indian Ocean ; Donax trunculus L., POLI 

 Testae, ulriusq. Sicil. n. Tab. 19, figs. 12 20, BLAINV. Malac. PL 71, 

 fig. 2, &c. 



(Capsa LAM. Lateral teeth none.) Sp. Donax Irasiliensis BLAINV. 

 Capsa Irasiliensis LAM., Encycl. metli., Vers. PL 261, fig. 10, BLAH 

 Malac. PL 71, fig. 3. 



Psammobia LAM. (and Sanguinolaria ejusd.). Shell transvt 

 subequilateral, subhiant at both ends. Hinge with two teel 

 more rarely with single tooth in each valve, lateral teeth noi 



