36 Proceedings of the Royal Irish Academy. 



Orehesellini. The five- or six-segmented feelers of Heteromuricus show a 

 correspondence with Orchesella, but this is a character tliat cannot be regarded 

 as of great importance, and the mncro of the spring (fig. 24), with its two 

 teeth and a slender inclined spine, is that of a typical Entomobryine. The 

 jaws, however (see below and next page), are in many respects like those of 

 Orchesella. Until further allied genera shall have been discovered it is, perhaps, 

 best to retain Heteromuricus as the unique representative of a distinct tribe. 

 The insects have a close superficial likeness to species of Tomocerus, on 

 account of the ringed feelers. From these, however, the form of the foot and 

 mucro, and the absence of spines on the dentes, distinguish them at once. 

 Moreover, in Tomocerus the third abdominal segment is longer than the 

 fourth, whereas in Heteromuricus the fourth is clearly longer than the third. 

 In the Seychelles collection a new species of this genus is represented by 

 numerous examples, which differ in many respects from H. cercifer Imms. 



Heteromuricus longicornis sp. nov. 



(Plates XV, figs. 20-2-i ; XVIII, figs. 74-77.) 



Feelers (fig. 20) nearly as long as the body, six-segmented; the proportional 

 lengths of the segments as 1:8:3:9:32:14, the fifth and sixth segments 

 (except for tlie proximal end of the former) ringed and surrounded with 

 wliorls of short, stout bristle (fig. 22). Eight ocelli on each side of the head, 

 the two posteriors of tlie inner row very small (fig. 21). Legs with scales 

 and feathered hairs ; a single filiform Itristle near the tip; claws with minute 

 internal teeth near the base, empodial appendage slender, lanceolate, 

 untoothed (fig. 23). Spring half as long as the body ; dens 1| times length 

 of manubrium (fig. 20), bearing long feathered hairs : mucro with evenly 

 curved teiminal and dorsal teeth, and a fine dorsal spine (fig. 24). 

 Length o'5 mm. Colour of scaling dark slaty-grey. 



Localities. — Silhouette (1908, 4 specimens). Malie : Foret Noire, 1000 ft. 

 (September, October, 1908, many specimens). 



This species is very easily distinguished from H. cercifer Imn)s, which 

 has the feelers only about half as long as the body, the eight ocelli all 

 about the same size, and the foot-claws with distal teeth. H. lowjicornis also 

 is apparently half as large again as H. cercifer. 



Opportunity has been taken from the number of examples of this insect 

 in the collection to make a study of the jaws, as the details of structure 

 known about the genus are scanty. There is nothing remarkable about tlie 

 mandible (Plate XVIII, figs. 74-75), except that the right one has, just 

 proximal to the apical tooth, four small teeth (fig. 74«), while the left 



