MUSEUM OF COMPARATIVE ZOOLOGY. 207 



at the tail than the large form. The body is a bright yellow, with bluish 

 black reticulations. The edge of the foot and the foot itself are almost black ; 

 shield irregularly mottled with fuscous ; the body also is irregularly mottled 

 with fuscous, and has one broad fuscous band down the centre of the back, 

 spreading as it joins the mantle, with a narrower band on each side of the 

 body. The other characters, external and internal, are given below. This 

 smaller form loses its colors on being placed in spirits, becoming a uniform 

 dull slate color. 



The large Olympia form is surely Avion foliolatus, Gould, agreeing perfectly 

 with his description in Vol. II., and with his figure in Vol. III., excepting 

 that the latter is colored with a deeper red. 



Mr. Hemphill writes of it : "I have to record a peculiar habit that is quite 

 remarkable for this class of animals. When I found the specimen, I noticed 

 a constriction about one third of the distance between the end of the tail and 

 the mantle. I placed the specimen in a box with wet moss and leaves, where 

 it remained for twenty-four hours. When I opened the box to examine the 

 specimen, I found I had two specimens instead of one. Upon examination of 

 both I found my large slug had cut off his own tail at the place where I no- 

 ticed the constriction, and I was further surprised to find the severed tail piece 

 possessed as much vitality as the other part of the animal. The ends of both 

 parts at the point of separation were drawn in as if they were undergoing a 

 healing process. On account of the vitality of the tail piece, I felt greatly 

 interested to know if a head would be produced from it, and that thus it would 

 become a separate and distinct individual." The animal on reaching me still 

 plainly showed the point of separation from its tail. (See Plate VIII. Fig. A.) 

 The tail piece was in an advanced stage of decomposition. I noticed the con- 

 striction towards the tail in one of five individuals of Prophysaon coivuleum 

 from Olympia. (See page 209.) Another individual of the same lot had a 

 truncated tail, having undergone the operation. The edges of the cut were 

 drawn in like the fingers of a glove. 



The tail of the Avion foliolatus having been cut off, I was unable to verify 

 the presence of a caudal pore from this individual. On the only living one 

 of the lot from Gray's Harbor, the pore was distinctly visible, and is figured 

 on Plate VIII. Fig. C. Usually, it seemed more "a conspicuous pit" than a 

 longitudinal slit, as in Zonites. At one time I distinctly saw a bubble of 

 mucus exuding from it. It opened and shut, and is still plainly visible on the 

 same individual, which I have preserved in alcohol and added to the Binney 

 Collection of American Land Shells in the National Museum at Washington. 

 Another individual from Seattle plainly shows the pore. 



Five specimens of the Gray's Harbor lot had, concealed in the mantle, a 

 group of particles of white limy matter which it was impossible to remove as 

 one shell plate. In the large Olympia individual these irregularly disposed 

 particles of lime, of unequal size, seemed attached to a transparent membranous 

 plate. With care, I removed this entire, and figure it. It is suboctagonal in 

 shape (Plate VIII. Fig. B). Under the microscope it appears that the par- 



