AN UNDESCRIBED LARVA FROM MAMMOTH CAVE. 137 



large plates, as iu other larvae. The frontal plate is here 

 very large relatively, and extends almost as far posteriorly 

 as the parietal plates, which latter do not meet, as ordina- 

 rily, behind it. In this regard the cave larva is very dif- 

 ferent from the larva of Chironomus, but agrees very closely 

 with larval Sciara. A slender projecting labrum forms a 

 sort of proboscis, and gives the head a strange look to one 

 accustomed to ordinary larvae ; but a close examination of 

 this part shows it to be very much like the larger and 

 wider labrums of Sciara larvae. Beneath, the labrum is 

 furnished with two parallel longitudinal series of hooks, 

 probably of service in rasping away the vegetable matter 

 used for food ; it is supported at its base by a dark brown 

 chitinous framework. The mouth is provided with a pair 

 of strong mandibles, followed by a sort of labium, prob- 

 ably representing two pairs of maxillae combined. Ex- 

 cepting the shape of the labrum, nothing about the head 

 as thus far described would necessarily separate the Mam- 

 moth Cave larva from larvae of Sciara which are common 

 among decaying vegetable matter in ordinary situations. 



The most singular feature of the head is a pair of large 

 oval ocelli which, in alcoholic examples, resemble fine 

 opals. From their prominence and size they are strongly 

 suggestive of the staring eyes of certain deep-sea fishes, 

 though of course their structure is very different from that 

 of the eye of a fish. The cornea is so transparent that 

 the tissues show clearly through it. It is not perfectly 

 continuous with the parietal plate, and the line of separa- 

 tion produces some appearance of an eye in a socket. 

 Beneath each of these enormous simple eyes is a small 

 black speck which appears to represent the eye-spots pres- 

 ent in Sciara and Chironomus larvae. 



The four segments which follow the head are tolerably 

 well marked, and each has a longitudinal fold on each side. 



