Chap. 6. 



INVERTEBRAL ANIMALS OF VERMONT. 



151 



FRESH WATER AND LAND SHELLS. 



fourtlis of an inch from the commence- 

 ment is a considerable depression in the 

 fin for more than half an mch, but it does 

 not amount to a division. The fia rays 

 are wiiite, minute and forked. The long- 

 est of three specimens before mo 5.3 inch- 

 es ; from the snout to the posterior bran- 

 chial opening ].l, to the vent 4.1. Rays 

 too small to be counted. 



History. — Tliis fisii agrees very well 

 with Kirtland's description excepting the 



depression in the dorsal, and that the 

 broadest part of the dorsal is some dis- 

 tance behind the vent. During the drought 

 in September, 1841, I found large num- 

 l)ers of these fishes, which liad buriec! 

 themselves in the mud at the bottom of 

 the small coves along the banks of Wi- 

 nooski river, from which the water had 

 evaporated. This fish is known in many 

 places by the name of Mud-Eel, or Blind- 

 Eel. 



CHAPTER VI. 



INVERTEBRAL ANIMALS OF VERMONT 



PrcUmbifinj Ohscrval'wii:. 

 Invertobral animals an^ such animals as 

 are destitute of a spine or back bone, and 

 are so e.xceedingly numerous that, with 

 the exception of the mollub.cous anunals, 

 we shall not even attempt to give a cata- 

 logue of them. The animals ol'ihis great 

 division are extremely various in their 

 structure, habits, and dispositions. Some 

 have their bodies protected by a shelly 

 rovcring, while others have their bodies 

 and limbs surrounded by crustaceous 

 plates, while, again, others have no other 

 covering than a soft and tender skin A 

 few only of them have red blood, and 

 none of (hem possess all of the five senses. 

 In many cases the sexes are united in the 

 same individual, and in some cases the 

 species is continued by a process some- 

 what resembling vegetation. They all 

 afford eminent manifestations o uie wis- 

 dom and skill of the Creator; and, though 

 generally regarded as insignificant and 

 contemptible, many of them contribute 

 largely to the comfort and interest of man, 

 while a still greater number are employed 

 in annoying and inju';ing him. 



Section I. — Mollusca. 

 Fresh- Wafer rmd Land Shells. 



Prepared expressly for this work. 



By Charles B. Adams, A. M., 



Professor of JVahaal History, Middlebury College. 



FAMILY PERISTOMIANA. 

 Genus Paludina. 

 Generic Characters. — Shell conoid ; whorls 

 conve.'i, modifying the aperture, which is ovate or 



nearly orbicular, mi'li ihc marf;ins unitctl. Opor- 

 ciiluni thin, corneous, concentric. Animal with 

 I he head short ; rostrum small anil truncate ; ten- 

 lades slentler, with the eyes on an enlargement 

 at their base ; foot broad, :hin. 



Paludina dccisa. — Say. 



Description. — Shell ovate -conic, with 

 revolving rows of bristly filaments when 

 young, smooth when mature, green ; apex 

 truncate ; whorls six, convex ; suture 

 deep ; spire a little longer than the aper- 

 ture, which 'S pyriform ; umbilicus very 

 small. Length 1.2-3 inch; breadth 0.75 

 inch ; divergence of the spine 58°. 



Remarks. — I'his species is very com- 

 mon in ponds and streams, and is found 

 near the water's edge partly buried in 

 mud or sand. Sometimes they are found 

 crawling at the distance of a few feet 

 from the water. They are viviparous, and 

 produce their young in May. These, at 

 birth, are furnished with a shell about an 

 eighth of an inch in diameter, globular, 

 and of a pale horn color, and are nearly 

 transparent. In the progress of growth, 

 the shell becomes proportionally more 

 elongate, and the part which was formed 

 previous to birth is invariably broken off. 

 They are very rarely found heterostrophe. 

 One such individual, of the size of a pea, 



