94 CLASS I. TROPIOPODA. ORDER I. BIMUSCULOSA. 



Cytherese which might have remained with more propriety among the 

 Veneres. The Cytherea concentrica and its cognate species have been 

 separated by Poli under the generic title of Artemis. 



The shell of Cytherea is described as being equivalve, inequilateral, 

 suborbicular, transverse or triangular, and either smooth or rough on the 

 outside. There are three divaricate cardinal teeth in one valve, with a 

 rather remote pit running parallel with the margin ; and four in the 

 other, one of which is remote, diverging laterally, almost sufficiently so 

 to be considered as a lateral tooth, and is inserted in the pit of the oppo- 

 site valve. The muscular impression of the mantle appears to be either 

 with or without a sinus, and the ligament is elongated and external. 



Examples. 



PI. LXIX. andLXX. Fig. 1. 



Cytherea petechialis, Lamarck, Anim. sans vert., new edit., vol. vi. 

 p. 299. Enc. Meth., pi. 268. f. 5 and 6. 



PI. LXIX. Fig. 2. 



Cytherea planulata, Sowerby, Proceedings Zool. Soc, 1835, p. 46; 

 Genera of Shells, No. 33. 



PL LXIX. Fig. 3. 

 Cytherea aurantiaca, Sowerby, Genera of Shells, No. 33. 



PI. LXX. Fig. 4. 



Cytherea concentrica, Lamarck, Anim. sans vert., new edit., vol. vi. 



p. 316. Enc. Meth., pi. 279. f. 2, a, b. 

 Venus concentrica, Linnaeus. 

 Artemis concentrica, Poli. 



PI. LXX. Fig. 5. 



Cytherea gibbia, Lamarck, Anim. sans vert., new edit., vol. vi. p. 323. 

 Enc. Meth., pi. 271. f. 4, a, b. 



