SERICODIAD/E. 15 



Body depressed, narrow. Head triangular. Eyes large and prominent. Neck very little 

 constricted. Prothorax short, channelled, widest anteriorly : with the angles rounded. Elytra 

 obliquely truncated at the apex, and emarginate, so that internally they terminate in an acumen. 

 Cubit emarginate. Tarsi with the penultimate joint entire. Claws single, not pectinated. 



The maxillary palpi of the genus here defined present an anomaly observed in no other known 

 coleopterous genus, they appear to be furnished with a minute fifth joint retractile within the fourth. 

 In one of these palpi, in the only specimen taken, this little accessory joint is not apparent, but in the 

 other it is distinctly seen emerging from the fourth joint, or rather, as this last appears broken at the 

 apex, it is uncovered. There is only one supposition that can reconcile this case to the general 

 rule, that no coleopterous maxillary palpus shall exceed four joints, namely — that this is an effort of 

 nature, by a reproduction, to restore the mutilated organ so as to fulfil its functions. Did the insect 

 belong to the Crustacea or Arachnida this would be a satisfactory explanation of the anomaly, but 

 I do not recollect any instance upon record of a genuine insect having reproduced a lost organ. 

 I thought it possible that the palpi of other Predaceous beetles might contain a retractile joint, and 

 this truncated apex seemed in some degree to favour the idea, but I did not succeed in my endea- 

 vours to discover one. 



The above structure of the palpi, if not accidental, seems to give our little insect some affinity 

 with the Subulipalpi of Latreille, but its general characters and aspect appear to demand a place for 

 it somewhere between those Truncipennia whose claws are not pectinated, and those who have those 

 organs so armed. 



(11) I. * Sericoda bembidioides. Bembidian Sericoda. 



S. (bembidioides J subtus nigra, supra nigro-renea, subsericea ; prothorace subtrapezoideo, posterius bifoveato : ehjtris substriatis 

 brevibus subnebulosis, apud suturamfovearum serie. 



Bembidian Sericoda, black underneath, above black-bronzed rather silky ; prothorax subtrapezoideal, with a pair of impres- 

 sions behind ; elytra substriated, impunctured, somewhat clouded, with a series of impressions adjoining the 

 suture. 



PLATE I, FIG. 2. 



Length of the body 3^ lines. 



Only a single specimen taken. 



Mr. Drummond, in answer to my queries with respect to this, and some others 

 of the more remarkable insects taken in the Expedition, observes, upon reading 

 my description of this insect, that it agrees with one taken on the sandy shores of 

 Lake Winnipeg in the spring of 1825, that it runs on the sands with great agility, 

 and frequently flies when attempted to be taken. But this statement agrees so 

 precisely with the motions of Bembidium impressum as described by Linne and 

 Gyllenhal (see under that insect) that I suspect Mr. Drummond had his eye to it, 

 rather than Sericoda. 



