203 



elsewhere in the forest of eggs, possibly of this species (Nos. 86 

 and 114), is of special interest. On the forested ravine slope (Sta. 

 IV, b) in another decaying stump, in which the bark was loosened 

 and the sap-wood quite decayed, soft, large examples of this slug 

 were found in abundance Aug. 17 (No. 89). They were associated 

 with newly established colonies of the carpenter-ant Camponotus 

 herculeanus pennsylvanicus, and the horned Passalus, Passalus cor- 

 mttus (No. 85). The association of these three species is not an ac- 

 cident, but indicates clearly a certain stage in the decay of a log or 

 stump which is favorable to their development. Another colony 

 was found under the bark of an oak stump (Sta. IV, b) in which 

 the sap-wood had decayed, but the remainder of which was solid 

 though discolored. A very large individual and several young slugs 

 ranging in length from about half an inch to an inch and a half were 

 found in a cavity under the bark Aug. 22 (No. 125). 



A batch of eggs, found with specimens No. 89, and presumably 

 of this species, was taken Aug. 17 (No. 86). These eggs, pearl- 

 like translucent spheres, twenty-two in number, were in a small clus- 

 ter. The other lot of eggs (No. 114) was taken Aug. 20 among 

 dead leaves and rotten-wood drift at the mouth of a ravine in the 

 lowland forest (Sta. IV, c), where Vitrea indentata was taken (No. 

 113). The large size of these eggs, which even when shriveled in 

 alcohol are over 2 mm. in diameter, the paucity of other large pul- 

 monates throughout these woods, the abundance of Philomycus, 

 and the presence of small young at this season are indicative that 

 the eggs belong to this slug. 



Little seems to be recorded concerning the life history of this 

 species or its habits. An individual kept by Binney (Bull. 28, U. S. 

 Nat. Mus., pp. 243-244. 1885) deposited thirty eggs June 30. These 

 hatched July 10 and grew very rapidly. Baker ('02, p. 203) states 

 that it ascends trees to a "height of over fifty feet, and is most fre- 

 quently found under bark which has become 'started' ." He also 

 states that it is "solitary in habit." My own observations of this 

 species confirm his statement as to its preference for wood in which 

 the sap-wood has decayed, but I have often found several specimens 

 in close proximity, as was the case with specimens No. 89. 



Endodontics 



Pyramidula altcrnata Say. Alternate Snail. 



A single dead shell (No. 173) of this common species in forests, 

 was taken at the mouth of a ravine in the lowland forest (Sta. IV, c). 



This is generally a woodland species. At Mackinaw Dells, along 



