118 HOMAMMATUS. 



armed at its inner surface with a basal tooth. The posterior femora 

 are incrassatecl, but not so broadly as in allied genera. The tibios 

 (Tab. IV. fig. 8 g) are inflected at their immediate base ; when viewed 

 from behind, the posterior surface is longitudinally grooved ; the 

 margination of this groove is subsinuate above the insertion of the 

 tarsus ; the apex is armed with a series of comb-like teeth, and ter- 

 minates in a robust incurved claw. The tarsus (Tab. IV. fig. 8 h) is 

 short and attenuate ; the first and second joints subequal, dilated at 

 their apex ; the third minute, almost circular ; the ultimate joint is 

 produced into a globular inflation : the claw is armed at its inner 

 surface with a short basal tooth. 



The two species which constitute this genus widely differ from all 

 other forms. Their very robust elytra (medially obliquely depressed), 

 and their small angulated thorax, designate them, prima facie, as 

 quite distinct from all other adjoining groups ; they differ, however, 

 inter se, and will probably at some future time, when we know 

 more of South- American insect-life, form the basis of two separate 

 genera. In H. turgidus the head is depressed, but not so abruptly 

 vertical ; the antenna? are obsoletely, not distinctly, incrassated (per- 

 haps rather filiform) ; and the thorax is more constricted in front, 

 and, as compared with the head, narrower. There is an absence, 

 also, of that peculiar glabrous and entirely impunctate surface of the 

 thorax. There may be traced moreover (under the microscope) a slight 

 variation in the relative forms andjengths of the joints of the palpi. 



1. Homammatus turgidus. (Tab. IV. fig. 7.) 



H. oralis, latus, subrotundatus, piceus; capite parum producto, ad 

 apicem oblique canaliculate; thorace quadrato, antice suhcon- 

 stricto, pube fiava sparsim obtecto, punctata ; < lytris si riato-punc- 

 tatis, ante medium complanatis, rotundatis, ad latera tenuiter 

 pubescentibus j antennis robustis, filiformibus, art. V"°— 5 f0 , 9"° et 

 10 mo flavis, 6'°, 7 mo , 8™ et ultima nigris ; pedibus flavis, femori- 

 bus posticis tarsisqut anh rioribus fuscis. 



Long. corp. 2i lin., lat. 11 lin. 



Oval, somewhat broad and robust, piceous. Head small, and 

 slightly produced ; from the base of the antennas two raised carina- 

 tions extend obliquely to the upper and inner margin of the eyes, 

 while between them is a third longitudinal carination which ap- 

 proaches medially the margin of the thorax : eyes prominent, situ- 

 ated at the base of the head, not extending laterally as far as the 

 anterior angles of the thorax : surface rugose. Thorax small, qua- 

 drate ; the anterior angles subacute and distinctly depressed ; the 

 sides marginate ; the surface is punctate, and clothed (as is apparent 



