228 GEOL. AND NAT. HIST. SURVEY OF MINNESOTA, 



teeth. The autenrite are long and when reflexed the sette reach nearly 

 to the posterior margin of the shell. The posterior angle is not always 

 as prominent as shown in Fig. 5, Plate LXI. 



*Acroperus angustatus Sars. 

 Plate LXII, Fig. 10. 



This species is distinguished from the former by the head, which 

 is higher and very strongly arched. The dorsal contour is nearly 

 straight. The antennae are shorter. The form of the post abdomen 

 of the male is less different from that of the female than in the above. 

 The length of both species is about 0.7 mm. 



The American form figured in Fig. 5 of Plate LXI differs from 

 both the above slightly. The head is carinated and incurved almost 

 as in G. angustulus; the antennae fall a little short of reaching the pos- 

 terior margin of the too low and oblong shell; there is an obvious de- 

 pression between the head and the body. However, in the main there 

 is close agreement with C. leucocephalus, to which it has been previously 

 referred. There is always a rudiment of an additional pair of feet. 



A. cavirostns P. E. Mueller, is not known in the female sex. The 

 male has a twisted caudal claw. It is probably founded on an ab- 

 normal individual. 



Acroperus alouoides Hudeudorff. 



This species is only known to me from incidental references in 

 Matile. The post-abdomen is said to be broader than in either of the 

 above. The claws have only one basal spine. The crest is low and 

 the macula is nearer the end of the beak than the eye. 



(Acroperus transylvaniciis Daday.) 



"Carina capitis rotundata; testa corporis dorsali leniter rotuudato; postice angulo 

 indistincto; margine ventrali I'ere recto angulum inermem formanti, cauda apice 

 rotundata incisa; unguibus caudalibus magnis, fere rectis. Longit 0.85 to 0.9 mm." 



The figures do not greatly fill out this hopeless description. The 

 form is short and so is the abdomen, but the armature of the latter has 

 nothing distinctive. 



SUB-GENUS CAMPTOCERCUS Baird. 



Although the general form is similar to the last section, the body 

 is usually longer; the post abdomen narrows toward the end; the anal 

 teeth exceed the lateral row; the antennfe have usually but seven 

 setse (in). 



The species enumerated are so closely related as almost to baffle 

 definition. 



