1 882.] American Work on Recent Mollusca in 1 88 1. 953 



Like many other synthetic, ancient types, the fossil representa- 

 tives were of colossal size compared with the living survivors. 



While some of the fossil forms were of moderate size, though 

 very large compared with Nebalia, some must have been of gigan- 

 tic proportions. For example, in Ditl : t p rneptumMatt, of which 

 Fig. 9 represents the telson and cercopoda of natural size, the en- 

 tire animal must have been some two feet in length. The Rchino- 

 caris punctatus must have been nearly a foot in length, while the 

 Echinocarides (Figs. 10 and 11), described recently by Mr. R. P. 

 Whitfield, were considerably smaller. 



AMERICAN WORK ON RECENT MOLLUSCA IN 1881 



( Contiiiu number.) 



Psychology, — Owing to the secluded life of most mollusks they 

 are not easily subjected to long-continued observation, and per- 

 haps for this reason notes on their affections or mental processes 

 are nearly unknown. But that careful observation would reveal 

 in many mollusks a much higher degree of intelligence than they 

 are usually credited with, there can be little doubt. A small con- 

 tribution to this subject is contained in the paper on "Intelligence 

 in a Snail," by the writer (Am. Nat. Dec. 1881, pp. 976-7)- The 

 observations there noted indicate that some species of the genus 

 Helix are capable of recognizing a call or sound, and of distin- 

 guishing it from other calls or sounds. Since this was printed the 

 writer has had information of two other cases, of the same kind, 

 though the facts are less clearly indicated than in the one first 

 mentioned. Dr. Lockwood's observations on Mytilus indicate a 

 certain degree of intelligence, and it cannot be doubted that obser- 

 vations on cephalopods would show that these highly organized 

 mollusks are capable of more or less complex mental operations. 

 Geographical Distribution and Catalogues.— In the Annals N. Y. 

 Acad. Sci. (11, pp. 1 17-126) in an article " On the relations of the 

 fauna and flora of Santa Cruz, W. I.," Bland shows, from a dis- 

 cussion of the land shells, that it is probable that St. Thomas and 

 other islands of the Virgin group were formerly connected with 

 Santa Cruz, but that in spite of a submarine ridge (with, however, 

 7oo fathoms of water over its greatest depression) extending to 

 Saba, there is no evidence of a dry-land connection of the latter 



