NATURAL SCIENCES OF PHILADELPHIA. 231 



anai processes, emarginate above, each projecting into a subtruncate point 

 iDferiorly ; legs long, slender, fulvous, posterior pair longest, anterior pair 

 with two slender black lines superiorly ; a black spot each side upon the 

 pectus, before the anterior and middle legs ; anterior tibia and tarsi pubescent. 



middle tibia armed with long cilia, posterior tibia . 



Length to tip of abdomen 15 millim., prothorax 2, mesothorax 4 millim. 

 Hong Kong, China. 



Gerris, Fab. 



G. rufo-scuteilatus, Latr. H. Schf. W. I. ix. 69. tab. ccc. fig. 924. 

 Simoda. 



PEDIRAPTI. 



Diplonychus, Lap. 



D. rusticus, Fab. ; Donovan, Ins. China, p. 46, pi. 19, fig. 1. Loo Choo. 



Nepa, Fab. 



N. rubra, Linn.; Donovan, Ins. China, p. 47, pi. 19, fig. 2. Hong Kong. 



NOTONECTID.E. 

 Bothronotus, Fieb. 



B. biimpressus. Robust, shining, dusky-yellowish testaceous; head 

 narrower than the thorax, with a punctured impression each side upon the 

 front, from both of which a punctured, impressed line extends to a shallower 

 impression, each side, near the base, apical joint of the rostrum piceous : 

 thorax transversely wrinkled, transparent, a transverse brownish band upon 

 the anterior submargin ; each side, behind the fossa, depressed ; scutellum 

 black ; corium with a pitchy stripe upon the interior suture, a spot at base and 

 against the apex, exterior submargin and membrane dusky; basal areole and 

 veins of the latter piceous; embolium and connected edge yellow; wings fuli- 

 ginous, veins darker; tergum piceous, posterior margins of the segments 

 paler, lateral margins and caudal extremity yellowish, the last clothed with 

 long golden hairs; venter pale piceous, middle carina and margins yellowish : 

 legs testaceous, clothed with golden hairs. 



Length 11 millim, breadth of thorax 5 millim. Hong Kong. 



Var. a. Pale, luleo testaceous, ventral disk and basal areole of the mem- 

 brane dusky. 



Notes on Shells, 

 BY T. A. CONRAD. 



In "Tertiary Fossil Shells of the United States," I characterized a genus of 

 Carditidce, published in 1838, under the name of Carditamera, which ha? 

 generally been referred to the genus Mytilicardia of Blainville. The two 

 genera differ so much in external form, that they can easily be recognized 

 without reference to the hinge. The former has the general form of an elonga- 

 ted Arca, Lam., whilst the latter has an outline somewhat like that of Modiola. 

 The genus Carditamera, Dr. Gray has since named Lazaria, the reason for the 

 change of name being unknown to me. 



In this country the genus Carditamera, originated in the Miocene perio'i. 

 which contains three known species, and there is one living, which inhabits the 

 coast of Florida. One is said to inhabit Madagascar, and all the others are 

 American. It does not appear that any species of Mytilicardia, is American, 

 either recent or fossil. The type of Carditamera is Cardita pectunculus, Brug. 



I860.] 



