75 



Its color and its dark obtuse peristome give rather marked char- 

 acters to a shell so small and simple. 



Amnicola egena. Testa minuta, tenuis, sub-perforata, elon- 

 gato-turrita, epidermide virescente induta : spira acuta, anfr. 5 

 convexis ; sulura profunda : apertura ovata ; peristomate con- 

 tinuo, labro acuto, patente. Long. I ; lat. y'j poll. Hab. Banks' 

 Peninsula, N. Zealand. 



More slender and less solid than A. hadia, and of an entirely 

 different color. It is very much like Paludina acuta of Europe. 



Lacuna carinata. Testa parva, tenuis, ovato-globosa, epider- 

 mide cornea tenui undulatim' striata induta: spira anfr. 5 ventri- 

 cosis, ultimo carina filosa cincto : apertura semicircularis dimidiam 

 testae adsequans ; columella rotundata. Long, y^^ ; lat. -^ poll. 

 Hah. Paget Sound. 



In color and marking much like L. vincta of our shores. Our 

 shell sometimes has the last whorl perceptibly angular, but it 

 never has the filiform carina. 



LirioPA DEcussATA. Tcsta parvula, perfragilis, acuto-conica, 

 badia; spira anfr. 8 convexis, transversim striatis, apicalibus 

 plicatis : apertura ovata antice subtruncata ; labro simplici ; col- 

 umella arcuata, antice unidentata. Long, ^^g ; lat. -^^ poll. 

 Found on floating wood, lat. 37° 40' N., long. 54° 30' W. 



Agrees well with L. striata, Pfeiff., except that it is less than 

 half the size. 



Mr. Desor exhibited specimens and gave an account of a 

 new species of Salpa obtained by him off the coast of Nan- 

 tucket. 



This genus is interesting as furnishing an instance of 

 alternation of generation ; one generation consisting of many 

 individuals united together in a common chain, the next of 

 separate individuals, and so on in alternate succession, each 

 kind producing the other. Mr. Desor gives to his new- 

 species the name Salpa Caboti. The genus Salpa had 

 been doubtfully classed, he stated, among the Mollusks. 

 It differs from them in the following particulars. The 

 intestine is reflected, and opens at the common orifice of the 



