CONCHOLOGY. 



with the Cardia and Tellina ; to the for- 

 mer they are more closely allied ; it was 

 originally established by Scopoli under 

 the name of Sphaenum^ this was changed 

 by Lamarck to Cylas, which is now 

 adopted by Latreille and other writers, 

 notwithstanding the previous application 

 of the term to a genus of plants. 



SPECIES. 



.1. C. Similis. Shell suborbicular con- 

 vex, base a little flattened ; with nearly 

 equi-distant, raised, concentric lines, giv- 

 ing a slightly sulcatecl appeai-ance to the 

 surface, and generally a more conspicu- 

 ous elevated darker wave, marking the 

 former year's growth of the shell. Epi- 

 dermis brown or ferruginous ; beak near- 

 er central and obtuse ; hinge with minute 

 very oblique teeth, lateral ones very dis- 

 tinct, elongated, and considerably resem- 

 bling those of the next species. 



Length seven-twentieths of an inch: 

 breadth two-fifths : a specimen measured 

 in length nearly three-fifths of an inch. 



Plate 1. fig. 9. 



Very much resembles Tellina Cornea 

 of authors; is found in plenty in the 

 river Delaware ; animal viviparous ; from 

 one specimen three pale yellow active 

 young ones were taken, the largest of 

 which measured in breadth three twen- 

 tieths of an inch in the month of May. 



2. C. Dubia. Shell oblique, subovate 

 convex, concentrically wrinkled, very 

 pale horn colour or whitish, with some 

 times a darker, but not raised band, 

 marking the preceding year's growth of 

 the shell ; beaks placed much nearer one 

 end; within whitish, primary teeth very 

 distinct, in one valve two divaricating 

 ones, in the other but one, exterior late- 

 ral laminal tooth very small. 



Length, five-twentieths of an inch ; 

 breadth, three-tenths. 



Plate 1. fig. 10. 



Inhabits the river Delaware in compa- 

 ny with C. Similis, and very much resem- 

 bles Tellina Amnica of Authors. 



GENUS CYHENA, Lam. 



Shell triagonally rounded, turgid, in- 

 equilateral, equivalve, robust; umbo 

 eroded or decorticated; hinge three 

 toothed in each valve ; lateral teeth 

 two, of which one is placed nearer to 

 the primary ones; ligament exterior placed 

 on the longest side. 



Obs.. This genus has been but lately 



constructed by Lamarck, to receive such 

 shells of the former genus Cyclas as have 

 three primary teeth on each valve. 



SPECTES. 



C. CaroKniensis. Shell cordate, turgid, 

 brown on the disk, with a yellowish or 

 greenish margin and sub-margin, surface 

 with numerous membranaceous wrin- 

 kles ; umbo much eroded ; beaks distant ; 

 two of the primary teeth caniliculate at 

 tip. 



Length, one inch and one-fourth ; 

 breadth, one inch and seven-twentieths. 



Cyclas Caroliniensis t Bosc. 



Inhabits the rivers of South Carolina, 

 and Georgia, but is not found so far north 

 as Pennsylvania. We found it in plenty 

 near Charleston, South Carolina, and in 

 St. Johns' River, East Florida, 



The shells here described are in the 

 collection of the Academy of Natural 

 Sciences of Philadelphia. 



It was originally the intention of the 

 writer of this article to insert here, not 

 only descriptions of the fresh water and 

 land shells, but those of the coast also ; 

 finding, however, that the descriptions 

 of the latter were by far too voluminous 

 to be comprised within the space allot- 

 ted to this article, and that they had 

 more generally found a place in the sys- 

 tems, the design is, with respect to this 

 work, necessarily relinquished. To all 

 the species here described, with the ex- 

 ception of three or four, we have been 

 constrained to adapt specific names; but 

 should it appear that we have been anti- 

 cipated by the labours of some recent 

 conchologist, whose writings we have no 

 opportunity to consult, we shall readily 

 bow to the right of priority, which ought, 

 unquestionably to be on all occasions im- 

 perative and exclusive. 



The primary divisions of the Linnaean 

 system, in the latest edition of the " Sys- 

 tema Naturae," as before observed, con- 

 sist of three orders, Multivalve, Bi- 

 valve, and Univalve, each of which is sub- 

 divided into genera. The Multivalves 

 contain the chiton, leapas and pholas: the 

 Bivalves, mya, solen, tellina, cardium, 

 mactra, donax, venus, spondylus, chama, 

 area, ostrea, anomia, mytilus, and pinna ; 

 and the Univalves, argonauta, nautilus, 

 conus, cypraa,r bulla, voluta, buccinum, 

 strombus, murex, trochus, helix, nerita, 

 haliotis, patella, dentalium, serpula, 

 teredo, and sabella. Which see. See 

 also SHELLS. 



