CRUSTACEA OF ALABAMA. 



37 



cording to Weismann, and the males appear but sparingly. The species S. mucronata 

 is very abundant everywhere, while the others are less frequently seen. 



Scapholeberis armata, Herrick. 



Scapholeberis mucronata, var. armata. Herrick. Am. Naturalist, 1883. 



A very beautiful and unique species, which possesses the extreme development of 

 the peculiarities of the genus. The head is shaped very much as in the previous spe- 

 cies, the fornix is squarish, the basin for the antennae is small. The upper lines from the 

 fornix meet behind the eye ; the form of the shell is as in the above, but the spines upon 

 the lower margin are longer. The scythe-like spine on the lower angles of the valves is 

 extremely long, falling little short, in extreme cases, of being as long as the entire lower 

 margin, in others about one-half as long. There are the usual lines parallel to the low- 

 er edge of the shell. The specimens having the longest spines were found in fresh water 

 about Mobile, Ala., but the species occurs in Minnesota and intermediate points, though 

 sparingly. 



It is beyond question that this species is of southern origin. It was noted in 1883, 

 that the spine of southern specimens average longer than those of the north. Moreover, 

 Gay describes a species from Chili, under the name of Daphuia spinifera which, as near- 

 ly as can be gathered from Schoedler's epitome, is almost identical with .S - . armata. 



It seems quite certain that the three nominal species S. nasuta, Birge, S. angulata, 

 Herrick, and S. aurita, Fischer, are local or other conditions of one species character- 

 ized by the more or less complete absence of the posterior spines of the shell, in which 

 case the latter name has the priority. The statement of Birge that the pigment fleck 

 is long rather than nearly circular or squarish is either due to an oversight or the confu- 

 sion of S. obtusa with the present species, though that species is not yet reported from 

 America. 



FAMILY LYNCODAPHNIDyE. 



The most abundant members of this family in Alabama are Macrothrix rosea and 

 Ilyocryptus spinifer, the latter being apparently of southern extraction. The accompany- 

 ing plate illustrates the structure of this anomalous genus and the relationship of the 

 various species. 



FAMILY LYNCEID^. 



The species most characteristic of the southern states is perhaps Lydigia quandran- 

 gularis, which is largely replaced northward by L. acanthocercoides. The American 



