On Aquatic Carnivorous Coleoptera or DytiscidcB. 685 



1072. ffithionectes optatus, n. sp. — Latus, anterius angustatus, subtus con- 

 vexus, nitidus, niger, capite antice, vertice maculis duabus, prothorace ad latera, 

 elytris signaturis transversim positis, antennis pedibusque anterioribus testaceis, 

 tibiis tarsisque posterioribus piceacentibus ; elytris epipleuris latis. Long. 12, 

 lat. 7 m.m. 



Fern., elytris versis basin in medio subtilisslme punctulatis. 



This species by its broad form, narrowed in front, by its markings and general 

 facias, presents a great resemblance to the South American Dytiscus interruptus (No. 

 1066) and its allies. The markings of the wing-cases consist of some spots close to 

 the base, forming a transverse band, and some other spots just behind the middle 

 forming another irregular band most distinct near the sides, and an apical yellow 

 mark which is much interrupted with black; the lateral margins also are vaguely 

 yellow. The sexual sculpture of the female elytra is so very slight, that it may 

 very readily pass unnoticed. I have seen only two females, which differ a good 

 deal in the distinctness of the yellow marks on the elytra. 



The specimen in my own collection was labelled in Mr. Saunders' collection, 

 " W. Afr.", the individual in M. de Bonvouloir's, "Guinee portugaise." 



Western tropical Africa, (Guinea). 975. 



I. 72.— Genus SANDBACOTTUS. 



Coxal lines obliterated, so that no supra-articular border is visible ; middle 

 femora with setee of moderate length. Elytra variegate with large yellow and 

 black marks. 



Ten species* are known, extending from India through Malasia to Australia. 



1073. Sandracottus hunteri, (Crotch,) Hijdaticus fasciatus, M.C. — Ovalis, sat 

 latus et convexus, nitidus, subtus niger, supra testaceus, vertice summo, prothorace 

 anterius et posterius in medio, elytris sutura, fasciis duabus transversis irregularibus 

 punctisque longitudinaliter dispositis nigris, antennis pedibusque anterioribus 

 testaceis, pedibus posterioribus nigricantibus, femoribus ssepe rufescentibus. 

 Long. 122, lat. 8 m.m. 



In the male the smaller palettes of the front feet are well developed, so that the 

 three larger palettes, which are only of moderate size and differ but little inter se, 



* Hydaticus baeri, Regt. (No. 1307 hiij. op.), near No. 1073 ; Manilla, should also be referred to tliis 

 genus; whether Colymbetes clairvillei, Mont. (No. 1217), New Caledonia, be a Sandracottus is doubtful. 



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