256 



head. The tentacles are closely appressed to the head, when out of 

 ■water, and are not discernible with a strong magnifier. 



The progressive movements of the animal are made by alternate 

 expansions and contractions of the foot, as in some species of Melania, 

 and suggest, as a comparison, the movements of certain caterpillars. 



This mollusk is found in moist grounds under bits of decaying wood, 

 leaves, etc., associated with several species of air-breathing moUusks. 

 The following species have been observed as its associates : 



Helix alternaia^ Say ; H. muUilmeata, Say ; H. monodon, Rackett, 

 ( Var. Leaii, Ward) ;* H. lucida, Drap. ; H. striatella, Anthony ; H. 

 cliersina^ Say; H. electriria, Gould; H. indentata, Say; Pupa contracta, 

 Say ; CarycJdum exiguum, Say ; and Succinea avara, Say. 



I am indebted to A. O. Currier, Esq., of Grand Rapids, Michigan, 

 for living specimens of this mollusk. and information respecting its 

 habits and associates. 



I have received specimens of Helix Leaii from Alabama, Ohio, 

 and Michigan. They are invariably smaller than either of the other 

 varieties known as monodon and fralerna, with a more open umbili- 

 cus, the shell of a darker tinge, usually brownish, with a ruddy tint 

 pervading the more solid parts of the lip, which is usually white in 

 monodon and fraterna. The soft parts are very much darker than 

 the soft parts of monodon and fraterna. The habits of the animals 

 confine them to damp localities where mojiodon and fraterna are never 

 found. There are two very strongly marked varieties of monodon 

 (umbilicus open) that have come under my notice. They are evi- 

 dently as distinct as H. hirsuta and H. stenotrema are declared to be 

 by Mr. W. G. Binney. I can hardly understand why Mr. Binney 

 should hold so tenaciously to H. stenotrema as a separate species, 

 .while he places fraterna and Leaii in the synonymy of monodon as 

 varieties. Certainly there are as good grounds for distinction in one 

 case as in the other. 



Prof. Wymaii exhibited a preparation of the bones of a 

 supernumerary leg from a goose. 



This was attached to the trunk on the left side near the tail, trailed 

 on the ground, and did not appear to be in any way under the control 

 of the will. It was connected with the body by the common integu- 

 ments and a thin layer of muscular fibres, which were attached to the 

 abdominal muscles on the right side ; another similar layer probably 

 existed on the left, but was Inadvertently cut away in the dissection. 

 Near its attachment was a small opening, connected by means of a 



* Helix Lean (Ward). This shell is very strongly characterized as a distinct 

 specie,«, both by the character of the shell and soft parts, and the habits of the 

 animal. 



