INSECTA MADERENSIA. 547 



dera, Ocalea and Tachyusa, along tlie margins of rivers and streams,— secreting 

 themselves between the loose stones and shingle at the water's edge. The mem- 

 bers of this last division (three or four of which enter our present fauna) in many 

 instances assmne the outward aspect of Calodera, their antennte being com- 

 paratively elongated, their movements marvellously rapid, and their whole surface 

 clothed (though in a less degree) with a short and silken pubescence, — a provision 

 which the species of that group would seem, from their semi-aquatic habits, so 

 eminently to requii-e, since theh constant liability to immersion renders it neces- 

 sary that they should be provided with some means for retaining a sufficient 

 amount of air to buoy them up, in case of accidents, and to enable them to float 

 safely to shore. Ilence it is not always easy, prima facie, to separate certain of 

 these riparial modifications from the Caloderce ; nevertheless an inspection of the 

 tarsi will generally succeed in distinguishing them, — those of the latter not only 

 being altogether pentamerous, but having the hinder pair almost as long as the 

 entu-e tibise and with the basal joint considerably produced*. 



§ I. Corpus apterum ; eJj/fris valde abbreviatis. 



415. Homalota sangrdnolenta, WoU. 



H. rufo-testacea et plus minusve infuscata subnitida, capite piceo, prothorace lato ad latera rotundato, 

 abdomine ultra medium subdilatato, segmeutis quatuor vel quinque baseos, antennisque versus 

 apicem nigrescentibus, pedibus testaceis. 

 Var. |3. omnino pallidior, abdomine iu medio solo nigrescente. 



Long. Corp. lin. Ij. 



Habitat sub lapidibus truncisque arborum prolapsis per partem Madera sylvaticam, pra;sertim in 

 humidis editioribus, toto anno frequens. 



H. rufo-testaeeous (and more or less obscured in parts), slightly shining, and apterous. Head more 

 or less brownish-piceous ; and with the eijes smaller than in the Homalota generally (nevertheless 

 considerably larger than those of Xenomma). Prothorax large and wide (with the sides rounded), 

 —being broader than either the head or elytra, which last are much abbreviated (although not so 



* Of these characters I am iucUned to believe that the structxire of the Under feet is iu reality the 

 most to be relied upon, seeing that the highest magnifying power will sometimes scarcely succeed in 

 satisfactorily detecting more than four joints iu the front tarsi of Calodera ; whilst, on the other hand, 

 undoubted Homalota do occasionally show traces, as it appears to me, of five. So decidedly have I 

 observed this to be the case, that I think it far from unlikely that lotli may, in point of fact, be penta- 

 merous,— the penultimate articulation being usually so closely soldered to the terminal one La Homalota 

 as to be altogether inseparable from it except under the deepest powers of the microscope. But the 

 supposed missmg joint does unquestionably seem to be indicated in some of the Homalotm which I have 

 recently examined, since I have not only been able to distinguish a transverse line across the lower por- 

 tion of the ^Masi-ultimate articulation, but, in some instances, even a slight projecting angle at the side, 

 — as though still further as it were to mark the junction. 



4 a2 



