16 WOOD, 



the Phalangid(B proper and the Gonyleptid(B , aud that 

 each of these groups is composed of several genera. A 

 large number of so-called genera have been named by 

 Koch in the work "Ueber sicht des Arachniden systems ;" 

 but have nowhere been described by that writer, at least 

 in no place that I have been able to find. A careful study 

 of the diagnoses of these genera as given by Meade,* has 

 produced grave doubts as to their distinctness ; and, cer- 

 tainly, it is impossible to rely upon the characters given 

 as separating natural, or even artificial groups. Phalan- 

 gium cornutum may be taken as the type of the Linngean 

 genus Phalangium, since the only species preceding it, in 

 the 12th edition, is not well known. Most of our Pha- 

 langid^ are members of one large generic group, and for 

 this the name Phalangium has been retained, since, in 

 the absence of specimens of P. cornutum, I have not been 

 aljle to find any characters distinguishing its members 

 generically from that species, although it is very possible 

 such characters exist. 



There has come under my notice but a single North 

 American species of the Gonyleptidee, which appears to 

 be a member of the genus Gonylej)te8 of Kirby. 



The specific characters are drawn from the spines, 

 tubercles, etc., on the surface of skin; — from the pattern 

 of coloration ; peculiarities of eye eminence ; of legs, 

 especially the trochanters ; from the size ; comparative 

 lengths of the body and legs ; and in the males, from the 

 genital appendage. There appears to be something 

 peculiar in the male organ of each species. For this 

 reason, although not proposing here to discuss the inter- 

 nal anatomy of the Phalangea3, it seems necessary to say 

 a few words as to the genitalia. The rather long, slit-like 

 genital openings in both sexes exist just posteriorly to 

 the point of attachment of the last pair of legs. The 

 penis, inclosed in a very pronounced sheath, extends 

 along the median line for nearly the whole length of the 

 abdomen. It is best exposed by slitting open the under 

 surface of the abdomen at the sides and turning back the 

 tegument like a flap. The sheath will then appear, and 



*Aunals and Mag. Nat. Hist., 1855. 



