PACKAED.] 



PHYLLOPODS OF NORTH AMERICA. 



331 



md 



o^ 



they are not varietal. It appears, then, that we have but one North 

 American species of Artemia so far as yet known. 



Upon comparing our s])ecies with the European it is difficult to find 

 good differential characters, as the portions of the body where specific 

 differences would be expected to occur are liable to considerable varia- 

 tion. Upon comparing a number of females from Great Salt Lake 

 with a number of females of the maleless generation from Trieste, Aus- 

 tria, received from Professor Siebold, there are really no differences of 

 importance ; our A. gracilis (Verrili's/er- 

 tilis) is slighter, with a smaller head, and 

 perhaps the 2d antennne are a little 

 slighter in build; I see no essential differ- _ 

 ence in the form of the ovisac, while the nix~-~--- 

 shape of the legs, especially the 6th eu- 

 dites, is essentially the same. The length P^^" 

 of females (as well as males) is the same 

 in both species. 



Upon comparing a good many males 

 from Great Salt Lake with several, both 

 stained with carmine and unstaiued, re- 

 ceived from Cagliari, Sardinia, throug'^h 

 Prof. J. McLeod, of Ghent, the European 

 A. salina is seen to be considerably 

 stouter, the head wider, the eye-stalks 

 longer and larger, and the eyes larger; 

 the frontal button-like processes of the 

 first joint of the claspers are nearly twice 

 as large as in the American species, and 

 a little more pointed, while the claspers 

 themselves are larger and stouter. The 

 legs and sixth endites are of about the 

 same form. The most apparent differ- tig. is.— Artemia gracilis, from Kew 

 ence is in the caudal appendages or cer- StlfV^^i^i^" '^"e? a'nfTst anSi 



COpods, which in A. salina are several a?i«', 2d antennse;md, mandibles,- ma;, max- 

 j.- 1 j_i -A -T -u • ■ illas; pes, foot; o, ovisac. 



times larger than m A. ^ra.c^M,9, being m 



the Sardinian specimens nearly three times as long and much larger 

 than in our species. In this respect the genus shows a close affinity 

 to Brancliinecta. However, in a lot of A. salina 9 from Trieste, the cer- 

 copods are very much shorter than in the Sardinian females, and only 

 a little longer than in our American specimens. These appendages do 

 not differ in the two sexes. 



As regards the genus in Europe, several nominal species have been 

 described, but it seems probable that but one occurs there. As stated 

 by Yerrill in his " Observations on Phyllopod Crustacea," in a foot-note, 

 owing to differences in the development of the caudal lobes and set«, 

 "several nominal European species, established mainly on differences 

 in the caudal lobes and setse, are probably only the young of others, or 

 all perhaps of A. salina, especially since those with small, caudal lobes 

 and few or no setse, are described as small ; ' as for example A.milhausenii, 

 A. arietina, and A. Mppeniana (Fischer species)." 



Verrill's types of A. monica I have not examined, but have certainly 

 found specimens at Great Salt Lake which agree with his description, 

 and especially his figures of the head and male claspers. 



Variations in Artemia fertilis from Salt LaJce. — With specimens of the 

 sexually mature males from Great Salt Lake the description of Yerrill 

 agrees weU, the claspers being very broad, the second joint being as 



