194 



REPORT — 1856. 



and Philippi states that it is not to be found even in the Royal libraries at 

 Berlin or Gottingen. Having fortunately obtained access to a copy of the 

 paper, and compared it with Mr. Nuttall's own shells*, and at the same time 

 with those brought by the officers of the Mexican war, I offer the following 

 as the best statement that present circumstances will permit. It should be 

 premised that Mr. Conrad, in the 'Journal' for 1849, made several emenda- 

 tions of his paper which have been here incorporated. The new species are 

 described in the ' Proc. Zool. Soc' 1856, pp. 209-229. 



* Mr. Nuttall's silvery locks have not lessened his interest in Natural Science. His 

 memory is singularly clear on all matters relating to his own collections ; and has been allowed 

 to turn the scale on doubtful points, in the few instances where no MS. had remained. 



f It is difficult to know what Conrad means by this genus, which is described in Journ, 

 1849, p. 214. He afterwards calls P. acuminata, which is clearly congeneric, Penitella Wil- 

 sonii ; while he applies the name Parapholas to Pholadidea melanura. It is here used accord- 

 ing to the interpretation of Woodw. (Man. Moll. p. 329) for the Pholadidea with tripartite 

 valves, persistent cups, and large plates. 



% Platyodon is described as a subgenus of Mya, with four testaceous valves on the ends of 

 the tubes. 



§ Cryptodon is described as a subgenus of Lutraria, with two corneous valves, which close 

 the orifices of the tubes. 



^ MytiUmeria, as appears from type valves in the Brit. Mus., received from Conrad, is a 

 subgenus of Lyonsia (not a synonym for it) with spiral umbos, regular rounded form, and 

 very slight ligamental pit. 



