202 [Fubruiuy, 



genus, agrees so well with that of O. cosfalis, that I quote part of 

 what he says : — " An approximate idea of the case may be formed by 

 imagining the bottom of a bottle to be cut away, and then its under 

 part to be compressed until the opposite sides touch each other, thus 

 transforming the wide circular opening into a narrow slit. The mouth 

 of the bottle represents the mouth-end of the larval case, and the long 

 narrow slit at the tail-end is held in an upright position. * * 

 For transformation the case is placed on one of its broad sides, and 

 then fixed on either side of each end by petiolated discs. * * After 

 having fixed its case, the larva turns its head towards the broader end 

 of it, so that the mouth-end of the larval case becomes the tail-end of 

 the pupa case."* 



Unfortunately, my larvje of O. costalis all died before they spun 

 up. I do not doubt, however, that the change of position above 

 indicated takes place, and the case is known to be fixed in the same 

 way (vide ante, p. 17). 



I am indebted to Mr. McLachlan for bringing before me a paper 

 (with a plate) by Mr. Gr. V. Hudson on the transformations of a New 

 Zealand species of IIydroptllidce.-\ The larva and case bear some 

 resemblance to those of O. costalis, but the case has a decided shoulder, 

 and there is no everted rim. No mention is made of how the case is 

 carried ; the figure suggests that it is trailed on the flat surface. The 

 alteration in position when the nymph stage is reached is noticed, as 

 well as the spinning of an arch-shaped partition towards the broad end. 



The second form of case to which I referred may belong to Ortho- 

 trichia angustella. I bred the insect, but the last ecdysis was not 

 quite complete, and the difficulty of an exact determination was 

 enhanced by the specimen being a $ . While this case does not share 

 the transparency of that of O. costalis, or even that of Agraylea, it is 

 not opaque ; the colour is greenish, the middle of the back mixed with 

 brownish matter. Form tubular ; ventral surface plane, dorsal gently 

 arched ; at either end (when viewed dorsally or ventrally) a large 

 triangular excision is seen, and this is unquestionably the strong 

 character of the case ; the apices of the triangles are connected by a 

 suture-like line, and the brownish dorsal part has a striated appear- 

 ance. When about to change, the larva fills up the triangles, produces 

 the sides into concave plates, and closes with silk. 



Head and thoracic segments of larva chitinous, narrow, of about 

 equal breadth ; head elongate-oval ; prothorax almost quadrate ; next 



Trans. Eut. Soc. London, 1879, p. 1-12. t Twus. N. Z. Institute, vol. xviii, pp. '213—4. 



