THE HEMIPTEROUS GENUS BELOSTOMA. 59 



lines in breadth. The colour and maculations are the same as in B. grande, though 

 the latter are not quite so distinct. The larva and pupa of this variety, do not differ 

 from the characters already given ; the former averages in length one inch, the latter 

 one inch seven lines. 



A species is found in the United States, especially in the Southern States, which 

 is confounded with the latter variety, but w^hich is very distinct, and as I can find no 

 special description of it, I will name it B. lialdemanum,* in honour of my friend Prof. 

 S. S. Haldeman, well known as a contributor to natural science. It is readily 

 distinguishable from the others by negative characters : its less robust anterior thighs; 

 the total absence of the double groove of the anterior thighs, and single one of the 

 tibise, although the trochanters are notched for the reception of the unguis ; and the 

 disappearance of the distinct maculations of the thighs and tibire. The specimens 

 measure from two inches to two and and a half in length, and from nine lines to one 

 inch in breadth. 



There are several smaller insects found in our waters of which I can find no 

 description, and which are generally referred to the genus Belostoma, to which they 

 bear considerable resemblance, but differ from it by very decisive characters. Since 

 the foundation of the genus Belostoma, several genera have been formed from it, but 

 whether they include the species I speak of, I am unable to say, not having access to 

 the proper authorities upon the subject, and will therefore describe them provisionally 

 under the name of 



PERTHOSTOMA. 



Body ovate, flattened superiorly ; abdomen sub-carinated inferiorly ; promuscus inflected in a state of repose, 

 cylindrical ; anterior exti'emity of labrum free ; eyes large, distant, saliant ; antennas very short, infra- 

 ocular, concealed, quadriarticulate, intermediate two articulations ramose, terminal one semi-elliptical ; 

 prothorax convex above, lateral margins convergent and somewhat emarginate ; hemielytra smooth with 

 the exception of a small round patch of pubescence at the inner angle of the coriaceous portion, where 

 it joins the membranous portion ; anterior legs raptorious, intermediate and posterior natatory ; anterior 

 coxse large ; anterior thighs very robust, with a double groove and intermediate ridge ; anterior tibia> 

 with a longitudinal groove ; posterior tibia; not more compressed than the intermediate, and less broad 

 than the thighs ; tarsi dimerous, divisions indistinct ; anterior pair with a single unguis, intermediate 

 and posterior with two ungues ; caudal seta; very short and spatulate. 



The principal marks of distinction l)etween Belostoma and Perthostosia, are, in 

 the form of the promuscus ; the form of the antennce ; the form, comparative size, and 

 situation of the patch of pubescence of the hemielytra ; the form of the posterior 

 tibise ; and the size and form of the caudal setae. 



*In accordance with the views of this gentleman upon scientific nomenclature, I have used a small initial to the 

 specific name instead of a capital. 



