STATE GEOLOGIST. 103 



0.5 mm. Schoedler says the lower margin is concave and the angle 

 unarmed, a condition not inconsistent with specific identity, as can 

 be seen in many other species. The shell seems to be variably 

 marked, but most conspicuous are the diigonal, curved strise. 

 Schoedler compares the sculpture to P. exiguus; Kurz, however, 

 leaves the impression that only slight reticulation is present in the 

 female. 



The male has the post-abdomen narrowed, ornamented with 

 clusters of hairs behind, and the small claws have no basal spine, 

 while the genital opening is in front of the claws. 



Sp. 2. Alonella pulchella. (Sp. n.) 



(Plate Q. Figs. 1—3.) 



A minute form very recently' obtained is described under the 

 above name. Although closely allied to A. exigua, this species is 

 more like Graptoleberis than any other member of the genus. It 

 is the smallest of the lynceids, excepting A. pygmasa. The shell 

 is high and rather strongly arched; the posterior margin is short 

 and armed with four teeth below, which point in different directions 

 as in Graptoleberis. The head is short and the antennules long. 

 The pigment fleck is of moderate size, but. smaller than the eye. 

 The post-abdomen is short, rounded below, and armed with sharp 

 and small anal teeth, besides which is an inconspicuous row of 

 minute setge. The claw is very small, and has a single very minute 

 tooth. The shell is marked by reticulations, which below are 

 regular hexagons but above pass into elongated meshes, and finally 

 on the beak and head become longitudinal striations. The areas 

 are lined as in A. excisa. Thus this species combines the form of 

 abdomen of A. exigua with the teeth of Graptoleberis and the 

 markings of A. excisa. 



Length hardly 0.27 mm. Motion active. The specimen figured 

 contained a single large ovum. The head may possibly have been 

 somewhat protruded by pressure. Habitat, vicinity of Minneapolis. 



Sp. 3. Alonella excisa, Fischer. 



(Plate E, Fig. 6; and Plate G, Figs. 10. 11.) 



Lynceits e.rcisus, fischek. 

 Pleurozus excisiis, schoedler. 

 AloneUa excisa, kurz. 

 / Pleuroxu-s insculptus, birge. 



This species is closely allied to Alonella exigua; yet that species 

 shows appreciable differences, (which can hardly be claimed, per- 



