THE NAUTILUS. 7 



In August, 1888, I collected on one occasion al)out a dozen exam- 

 ples of Prophysaon andersoni J. G. Cp., near the San Jose reservoir, 

 above Lexino-ton, Santa Clara County. AVhile taking measurements 

 of the living s|)ecimens, l)efore putting them into alcohol, I noticed 

 in several a contraction about t\v(>-thirds of the length from the 

 head. This appeared as an indented line completely encircling the 

 body. Upon handling the slugs to examine this phenomenon more 

 closely, the line became deeper and in the case of two of the speci- 

 mens the tail dro])ped off, almost as readily as the ray of the so- 

 called "brittle" starfish. Only with mature slugs did this happen. 

 The young, constituting the majority of those captured, showed no 

 signs of shedding their tails. Perhaps they had further use for them. 

 The discarded appendages showed vitality for a short time only, 

 when they went to join their owners in my collecting bottle. 



Again, only a few weeks ago, I collected on the northern 

 boundary of Oakland some Prophysaon hemphilli Bl. ct Binn. which 

 together with Ariolimax Californicus and one of our smaller species 

 of Ariolimax, inhabit a marshy spot near the Bay shore. At home 

 the next day when taking my captives out of the can into which 

 they had been put, I noticed the same contraction taking place in 

 the specimens of Prophysaon, but in no case did it proceed to dis- 

 memberment. I put them into alcohol and in every one of them, 

 seven in all, there is a well-marked, depressed line about the body 

 near the tail, the body being attenuated behind the constriction, the 

 whole looking very much as a soft iron wire looks just before it 

 breaks under a tensile strain. In the largest specimen which 

 measures 34 mm. contracted in alcohol, the depressed line is 8 mm. 

 from the tail and is marked across the foot by a black line, as if the 

 tissues were already almost severed. When collected there was no 

 constriction visible. 



In no other case have I observed this dropping of the tail among 

 slugs, which seems as far as recorded to be confined to species of 

 the genus Prophysaon. Here are the facts ; who can explain them? 



NOTES ON SOME NORTH AMERICAN PUPID^E WITH DESCRIPTIONS 

 OF NEW SPECIES, 



BY DR. V. STERKI. 



On ray request, Mr. H. Hemphill, of San Diego, Cal., was so 

 kind as to forward to me, for examination, all the North American 



