FROM THE MERGUI ARCHIPELAGO. 



257 



few anterior elytra meet in the middle dorsal line, the rest leave 

 the dorsal surface uncovered in the middle line. 



With regard to the shape of the elytra, Grube finds that in 

 P. rnelanonotus some are bell-shaped * ; and that therefore this 

 generic distinction must fall to the ground. 



This species (P. rnelanonotus) agrees with Kinberg's definition 

 of the genus in so far that a few of the anterior pairs of elytra 

 meet in the middle dorsal line, while the remainder do not. Not 

 so, however, P. nigromaculata. In this species the anterior 

 elytra do not meet in the middle dorsal line, while the posterior 

 do, as in Eupompe. The Mergui species is a connecting-link be- 

 tween the extremes ; the three anterior pairs of elytra, as well as a 

 large number of the posterior pairs, do meet in the middle dorsal 

 line, while the elytra of intermediate position do not. It is clear, 

 therefore, that the arrangement of the elytra is only of value as 

 a specific distinction. 



The only remaining generic distinction t is the pharynx. 

 Grube says nothing about this, probably for the same reason 

 as myself, being unwilling to injure the only example of the 

 species contained in Dr. Anderson's collection. 



Even if the differences in the pharynx of the type species of 

 the genera described by Kinberg are found also in other species, 

 it appears to be largely a question of opinion and of authority 

 whether the difference is sufficient to constitute a generic dis- 

 tinction. In my own opinion the comparatively slight modifi- 

 cations in an organ, which often undergoes such variations in 

 closely allied species, as in the case of Nereis, cannot be con- 

 sidered of sufficient importance to warrant a generic separation. 



The specimen measures about 110 millim. in height ; it is of an 

 elongated form, only slightly narrowed towards the posterior 

 extremity. The colour is of a yellowish brown ; the elytra are 

 coloured of a rich brown, which is rather more conspicuous on 

 the inner side. The dorsal side of the body, as in other species, 

 is covered with closely-set wrinkles, which render it impossible 

 to map the segments in this region ; on the ventral side the 

 intersegmental furrow r s are obvious. 



The dorsal surface is marked by a median longitudinal dark 



* Loc. ext. p. 49. 



f The difference between the setse is not referred to in the generic definition, 

 and can hardly be regarded as of generic importance. 



