ZOOLOGY. 785 



in the shell, and the shell more or less developed, spiral, thin, and trans- 

 parent. The iSTorth American species are all referred to the genus Suc- 

 cinea by Mr. Biimey, and twenty-six species are recognized. 



All of the forms now noticed belong to the group Monotremata (or 

 Syntremata) as previously noted, and only four species belong to the 

 remaining two families of Ditremata. 



The Veronicellidse have a "jaw slightly arcuate, with numerous ver- 

 tical ribs;" teeth differentiated into (1) "centrals, narrow, unicuspid, 

 with expanded sides," (2) "laterals large, obscurely tricuspid," and with 

 "medium cusp sharp and long," and (3) "marginals with quadrate 

 base short, triangular, unicuspid," and mantle not distinct from general 

 integument ;" the shell is entirely suppressed. Two species have been 

 found in the United States, one in Florida and the other in California; 

 both are terrestrial. 



The Ouchidiidse have the "jaw entirely smooth or lightly wrinkled," 

 teeth differentiated into " central tooth, tricuspid lateral teeth, and margi- 

 nals with quadrate base, razor-shaped," having the "base long and with 

 cutting j)oint narrow" and "medium cusp truncated and verj' long;" the 

 mantle is " thick, more or less tuberculous above," and no shell is de- 

 veloped. The two North American species belong to the genus Onchi- 

 della, one (O. borealis) occurring from Prince William's Sound to Van- 

 couver's Island, and the other (O. Carpenteri) from the Straits of Fuca 

 to the Gulf of California. 



Differences among the slugs. — Some of the European malacologists ad- 

 mit numerous species of Slugs as of the families Limacidse and Arionidie 

 on slight differences of form, proportions, and coloration, but the pro- 

 priety of so doing has been questioned by Mr. S. Jourdaiu, who thinks 

 that the differences that have generally been made use of for specific 

 distinctions vary with age as well as habitat. He therefore urges that 

 investigation should be directed to the internal organs and es])ecially to 

 the arrangement of the generative apparatus. "The pedal gland is also 

 of service ; it contains a cylindrical excretory canal which extends 

 more or less along the median line, and receives the mucoso-glandular 

 secretions of the lobules of a racemose gland on either side of it ; the 

 internal face of the canal is vibratile. In the Limacida) it arises as an 

 invagination of the ectoderm, and subsequently becomes branched; the 

 extremities of the branches are invested by mesodermic cells which rap- 

 idly become secretory." On differences discernible in the characters in 

 question, Mr. Jourdain distinguishes five species occurring in the en- 

 virons of St. Vaast-la-Hougue : these are four of the family Limacidai 

 and one of xYrionidse. {Gomptes Rendus, Acad. Sci. v. 101, pp. 963-96G. 

 J. R. M. S. (3), V. 10, p. 50.) 



An European Faloeozoic land shell. — Until lately, no land shells have 

 been found in the palaeozoic rocks outside of North America, but in the 

 H. Mis. 15 50 



