175 



a long time before becoming a pupa, and the perfect insect 

 will then not be disclosed before the second summer after- 

 wards in the month of June. I should not forget to state that 

 when the caterpillar is at rest on the plant, it raises the fore 

 part of the body, and if disturbed wags it violently from side 

 to side. The head of the young larva is armed on the occiput 

 with two little corneous tubercles, which, however, disappear 

 after two or three moultings. This insect is the Notodonta sex- 

 guttata of my MS. ; but I wish some competent person would 

 compare the moth with Tliyatira batis, and let me know if it 

 may not be near to that species in generic characters. 



My No. 38 (a very common insect here, and a form of which 

 we have several species) you referred in one of your letters to 

 Ophiusa crassiuscula. The discovery of the larva by your 

 little namesake removes the insect to another group, and proves 

 it to be a true EucUdla. Edward's specimens made cocoons 

 of a dried leaf, interwoven with a little silk, in 

 which the larvse were changed to pupse, cov- 

 ered with a bloom like that of the pupa of 

 Catocala, The attitudes of the larvse, which 

 I have tried to represent, are vjery odd. Color ^^^- ^^• 



brownish white, with darker longitudinal 

 stripes, and two black dots ^ on each side of 

 the body. The species is the Noctua gemina 

 Fabr., erectJiea Cramer. 



I have also sketched three forms of Lima- ^Jg- 27. 



codes, making, with Smith- Abbot's pithecium and cippus, five 

 different forms of the American species of the genus. Some 

 writers state that the prolegs in Limacodes are retractile. 

 This is not true of our American species, which are entirely 

 destitute of prolegs. The alternate contraction of the muscles 

 attached to the abdominal folds serves, instead of prolegs, to 

 assist the insects in movino;. 



The larva, represented on the left [PI. ii, fig 10], stings by 

 means of the prickles wherewith the tubercles are beset, and 



