1886.1 133 



below it, white, but interrupted and not very conspicuous ; and below these is 

 another stiarcely so pale line along the spiracles ; hairs and the distinct tubercles 

 white. Ventral surface and prologs greenish-olive, anterior-legs shining black, 

 ringed with paler. 



Var. II has the ground-colour bright pale green ; head as in Var. I ; the pul- 

 sating dark smoky vessel — in some specimens tinged with pink anteriorly — forms the 

 dorsal stripe ; sub-dorsal lines indistinct, whitish ; below these is another line, but 

 much interrupted and broken into short lengths ; there are no lines along the 

 spiracular region ; hairs and tubercles white. Yentral surface and prolegs of the 

 bright green of the dorsal area, the legs shining black, ringed with white. 



From the foregoing it will be noted, that the chief points of distinction between 

 this insect and cosniodactylus — distinctions which will probably be found to be 

 reliable — are : the deep purple ground-colour in acanthodactylus, as compared with 

 the " purplish-pink " of cosmodactylus ; the white sub-dorsal lines being less con- 

 spicuous in acanthodactylus ; and the head being yellowish-brown marked with 

 black, in place of the " very dark sienna-brown, almost black," in cosmodactylus. 



Uuddersfield : October 8th, 1886. 



A LUMINOUS INSECT-LARVA IN NEW ZEALAND. 



BY C. R. OSTEN-SACKEN, Hon. F.E.S. 



Mr. Hudson's account {ante, pp. 99-100) about the luminous 

 insect-larva from New Zealand leaves me very little doubt that it 

 belongs to tbe MycetopUlidcB. Tbe description of the "glutinous 

 web," the rapid motions of the larvae gliding upon it, and their retreat 

 into holes, when alarmed, show a remarkable agreement with my 

 observations on the larvas of Sciophila, described in detail in my 

 article: " Characters of i}ie\a.vxsd oithe Mycetophilidw,'' in the Pro- 

 ceedings Entom. Soc. Philad., 1862 (I have recently reprinted this 

 article as a separate pamphlet for distribution among my correspond- 

 ents). Whether my Sciophila larvse were shining or not, I can neither 

 affirm nor deny, because I do not remember seeing them in the dark. 

 But we have another observation of luminous larvse of Mycetophilidce, 

 that of Wahlberg, Act. Holm., 1S38 and 48. He observed the trans- 

 formations of Ceroplatus sesioides, and saw larva and pupa, but not the 

 perfect insect, emit a bright light. His paper will be found translated 

 in the Stett. Ent. Zeit., 1849, pp. 120—123. There is no doubt now 

 that the fly Trimicra pilipes was bred from some other larva hidden in 

 the mud which contained the luminous larvse ; one of the " small 

 earthworms " mentioned may have been that very larva. To make 

 assurance doubly sure, I wrote to Mr. Theod. Beling, in Seesen (in 

 the Harz mountains), who reared larvje of Trimicra, and published 

 descriptions ; upon my suggestion he took the trouble to hunt up such 



