1879.] NATURAL SCIENCES OP PHILADELPHIA. 201 



the accompanying cut of the head of the male. The front of ihe 

 head is prolonged into a straight beak, which hangs down nearly 

 vertically between the first joints of the claspers, and is flattened 

 antero-posteriorly, and emarginate at its tip. The antenniform 

 appendage is much longer than in S. texanus, Packard, whilst the 

 terminal branches of the claspers are widely different from those 

 of that species in their shape and relative proportions. The male 

 organs are very feebly armed with a few short spines, and are 

 nearly straight. 



The cephalic horns of the female are twisted upon themselves, 

 slightly bent and flattened at their extremities, which are fringed 

 with short hairs. The large lateral, ovoid, pedunculate, apparently 

 glandular organs behind the eyes, are the same in size and shape 

 in both sexes. The ovigerous sacs are large, nearly half as long 

 as the abdomen, conical in form, and contain a great number of 

 ochraceous eo;2;s, more numerous and much smaller than those of 

 Chirocephalus holmanii from the same locality. The male is of a 

 beautiful green, deeper about the head, as though saturated with 

 acetate of copper; the female, on the other hand, is yellow with a 

 tinge of green, verging to brownish in parts, and is very nearly 

 of the same size as the male, if not a little larger. This similarity 

 in the size of the sexes, with a tendency in the females to be 

 largest, is observed only in S. torvicornis, as far as I am aware. 

 The two rather long, plumose, tapering branches of the tail are 

 red in both sexes, but of a much brighter red in the female ; more 

 slender in the male. Length 2*7 mm. 



I name the species for Mr. W. P. Seal, who collected the first 

 t} T pical specimens ; the same gentleman has since furnished me 

 with an additional supply of examples. 



The known species of this genus are accordingly as follows : 



Streptocephalus torvicornis, Waga, % 1 inch, 9 about 14 lin., 

 Warsaw, Poland. 



S. cafe?*, Loven, 15 mm. long, Cape of Good Hope. 



S. similis, Baird, % 8 lin., 9 6 lin. long, St. Domingo. 



S. texaiius, Packard, % .65 in., 9 .55 in. long, Texas. 



8. watsonii, Packard, 1G mm., 9 12-18 mm., Ellis, Kansas. 



S. sealii, Ryder, 27 mm. long, New Jerse}'. 



All of the species are found in fresh water. 



The distribution of the species of the foregoing genus, and the 

 resemblance existing in some features between the Polish and New 

 14 



