OP WASHINGTON. 115 



Described from two specimens found by myself on April 

 i gth, in the semi-tropical hammock of the island of Key West, 

 Fla. ; precise food-plant unknown. 



In the female of C. punctatissimus the antennal scape is 

 much more slender than in the male, not dilated, and with the 

 terminal edge rounded ; the club is smaller, longer than wide, 

 and more regularly oval. The female of C. spinifer will pre 

 sumably participate in these characters, and further differ 

 from the male in the sculpture and vestiture of the head and 

 in the absence of the antennal spine. Aside from the differ 

 ence in size and sculpture the two species of Corthylus may be 

 distinguished as follows : 



Klytral declivity simple ; antennal club with two straight sutures, and 

 unarmed in both sexes .punctatissimus 



Elytral declivity retuse, margined at apical third, and provided each side 

 with three small tubercles ; antennal club with three sutures (the 

 two outer ones curved), and armed, in the male, with a long, curved 

 spine spinifer 



Mr. Marlatt presented the following paper : 



THE FINAL MOLTING OF TENTHREDINID LARVAE. 



BY C. L. MARLATT. 



In my experience in rearing the larvae of various Saw-flies, 

 I have been repeatedly struck with the surprising and appar 

 ently anomalous change, just before spinning up or entering 

 the ground to pupate, in coloration only in the case of the 

 smooth-bodied forms, and with spiny larvae in the loss of the 

 spines, accompanied with similar colorational changes. The 

 variation of larvae in this particular was so marked that it was 

 difficult to believe that one was dealing with the same species. 

 The larvae of totally distinct species could not present more 

 decided differences. 



At first the nature of this change was not comprehended, 

 but later it was found that after full growth is reached and the 

 usual four meltings are undergone, what I have termed the 

 final molting takes place. This molting is as complete as any 

 of the others the entire skin being shed, including that of 

 the head and thoracic feet and I believe has no counterpart 

 in any other family of insects. In L,epidoptera the hairs 

 in many species, or fleshy appendages, as in certain of the 



