this family is viviparous, that is, brings 

 forth its young alive, instead of laying 

 eggs, as in the family Limnaeidae. This 

 character has given the family its name, 

 which is certainly well chosen. When 

 born the shell is about one-sixteenth of 

 an inch in length and is perfectly trans- 

 parent. The animal is very active and 

 eats voraciously of any vegetation within 

 reach. Another handsome shell belong- 

 ing to this group is the Vivipara contec- 

 toides, which is about an inch in length 

 and is encircled by several color bands. 

 It is a common shell in many of our 

 ponds. 



Somewhat larger and handsomer than 

 the Viviparas are the Ampullarias, or ap- 

 ple-shells (also called idol-shells and 

 pond snails). These animals live mostly 

 in tropical and subtropical regions and 

 are noted for the tenacity with which they 

 retain their hold on life. So tenacious of 

 life are they that instances are known of 

 their living for several years away from 

 the water, in this respect resembling some 

 of the land snails. It is also recorded that 

 hollow pieces of logwood from Honduras 

 have frequently contained specimens of 

 this family alive after a journey of thou- 

 sands of miles. They may be said to be 

 truly amphibious. 



The writer has collected in Florida the 

 large Ampullariadepressa in considerable 

 numbers. It was noted particularly that 

 this species furnished the principal food 

 of the Everglade Kite, a bird inhabiting 

 the southern part of Florida. Large 

 quantities of these shells were found 

 about the nesting places of these 

 birds, from which the animal had been 

 neatly extracted without damaging the 

 shell in the least. The bird is, curiously 

 enough, provided with a curved bill which 

 easily fits into the aperture of the mollusk 

 and extracts the animal with little dif- 

 ficulty, and the feet and claws are so con- 

 structed that the shell may be firmly held 

 during the operation. This shell is fig- 

 ured on the plate. 



In Central Africa there is a lake, Tan- 

 ganyika, having a length of four hundred 

 miles and a width of from ten to fifty 

 miles, and at an elevation of twenty-seven 

 hundred feet above sea level, which has 

 one of the most interesting and peculiar 

 fresh-water molluscan faunas known. It 



is thought that at some remote period in 

 geological history this lake formed a part 

 of the ocean and that in the course of 

 time it was cut off from the sea, grad- 

 ually became fresh and was finally raised 

 to its present elevation. The reason for 

 such a theory is the presence in the lake 

 of certain molluscan organisms whose 

 shells closely resemble those of the salt 

 water family, Littorinidae (Periwinkles). 

 The fact that certain species of the family 

 inhabit brackish water and are even sub- 

 ject to the influence of fresh water, adds 

 additional weight to this theory. The 

 shell of this species (Limnotrochus 

 thomasi) also resembles certain of the 

 top-shells (Trochus), which are marine in 

 habitat. Most of the other species in- 

 habiting this lake are like the fresh water 

 Viviparas in form. 



The animal of Ampullaria depressa is 

 very curious and interesting when studied 

 alive. The foot is very wide, almost 

 square in some positions ; the head is 

 narrow, separated from the body by a 

 neck and the region of the mouth is pro- 

 duced into two long, cylindrical, tapering, 

 tentacular processes, which are probably 

 tactile organs like the elongated lips of 

 Glandina, described in the last article. On 

 the top of the head are placed the two 

 whip-like tentacles, which are longer than 

 the length of the whole animal and are 

 always waving about when the animal is 

 in motion. Just back of the tentacles the 

 eyes are placed at the end of two short, 

 rounded prominences or peduncles. 

 From the left edge of the aperture extends 

 the long, hollow, cylindrical siphon 

 formed by two extensions of the mantle. 

 On the upper side of the posterior end of 

 the foot is placed the horny, concentric 

 operculum or door. When the animal 

 withdraws into its shell the head first dis- 

 appears with its appendages and the 

 siphon, and the foot is doubled up in the 

 middle, the operculum shutting in last 

 and closing the interior against all ene- 

 mies. 



All of the different groups of the mol- 

 lusca have their giants and their pigmies 

 and the fresh-water mollusks are no ex- 

 ception to the rule. We have thus far 

 studied the animals of normal size and 

 the giants. Let us now turn our attention 

 to some of the pigmies among the fresh- 



