142 MONOGRAPHIA 



42. NIRMUS PODICEPIS. Denny. (Louse of the Grebe.) 



Plate X. Fig. 9. 



Elongate ; head and thorax pale ochraceous yellow ; ab- 

 domen pale, yellow-white, each segment with a triangular 

 black mark on the side. 



Pediculus Colymbinus ? Scopoli, Faun. Carniol. 384. n. 1045. 



Head elongate, conical ; clypeus produced, a transverse 

 fascia in front, an interrupted lateral band, and two longi- 

 tudinal impressed lines at the occiput, deep chestnut; vertex 

 depressed, base concave, temporal lobes produced; eyes 

 flat, and rather obscure; antennae slender, pale, yellow; 

 trabeculae fuscous, short, and conical ; prothorax as wide as 

 the head, lateral margin rotundate and black, centre chan- 

 nelled; metathorax oblong, sub-trapezoidal, with a black 

 lateral fascia, posterior margin rotundate, setose at the 

 lateral angles ; abdomen lanceolate, each segment with a 

 triangular black patch on the lateral margin, extending 

 towards the median line; legs rather thick, pale, testaceous, 

 yellow. Length 1. 



I have found this species upon the Little Grebe (Podi- 

 ceps minor), and received specimens from my brother taken 

 upon the Great-crested Grebe (Podiceps cristatus), in Nor- 

 folk, also a single specimen from the Red-necked Grebe 

 (Podiceps rubricollis), which I have been much perplexed 

 with, whether to consider as a variety only of the present, or a 

 distinct species. It agrees with the present species, in size, 

 form, and general character, but differs as follows : The 

 head and thorax are deep fulvous yellow ; the abdominal 

 segments bright fulvous on each side, with the triangular late- 

 ral patches deep chestnut. This difference however is not 

 greater than we find between the adult and immature state 

 of some species, which I almost suspect these will prove ; 



