352 GEOLOGICAL SURVEY OF THE TERRITORIES. 
its fellow of the opposite side when in repose). The two frontal ap- 
pendages (Pl. XIII, figs. 4, 5) very long, coiled, and twisted, with 
the appearance of being jointed, and gradually diminishing to a long, ~ 
eurved point, which is minutely spinulated, the spimules short, stout 
at base, and acute at tip; variously and finely lobed with about seven 
finger-like spinulated processes, best marked in old males (Fig. 22); near 
the middle a group of four 
or five sete. These organs, 
when stretched out, are 
about three times as long 
as the male claspers. As 
a rule the 6th endites of 
~ all the feet are narrow and 
obtuse at the end, much as 
in Branchipus, the gill vary- 
ing much in size. The 
head of the female is sim- 
ple, without any frontal ap- 
pendages; the ovisac is 
short and small, contain- 
ing about a dozen very 
large eges, showing that 
the number of individuals 
Fic. 22.—Chirocephalus holmani; male. Front view of headjn this species is far less 
of male, much enlarged, the frontal appendages somewhat re- wie Re 
tracted; ai’, first antenna: ai’, second antenna or male clasper, than in the other species of 
watiee spur and filiform 2d joint; fa, frontalappendage. Giss- the family except, perhaps, 
Artemia. 
Total length of body of male, 15™"; of 2d antennae, 3™™; of frontal 
appendages when outstretched, 5-6""; of genital organs, 2°"; caudal 
appendages, 2-2, 3”". 
Total length of female, 16™™; of ovisac, 2™™. 
I have received the ¢ and 2 from Mr. Ryder, the types of his descrip- 
tion, and also a number of both sexes, the females with eggs, from Wood- 
bury, N. J., near Philadelphia, collected in company with Branchipus 
vernalis, March 27, by Mr. William P. Seal; also from Glendale, Long 
Island, from Dr. C. F. Gissler, who kindly sent me a drawing of the 
head of an old male, although the sketches of the head of the male 
by Mr. Ryder in the Proceedings of the Philadelphia Academy of Sei- 
ences are truthful to nature. 
This Branchipod is certainly, only excepting the next genus, the most 
interesting and bizarre of all our fresh-water Phyllopods. The sketches 
in Plate XIII will convey a better idea of the form of the feet than any 
verbal description. 
Subfamily THAMNOCEPHALIN® Packard. 
Body large, very stout and thick; eleven pairs of feet; 2d male an- 
tenne with the 2d joint simple, curved; nine abdominal segments; ab- 
domen broad and flat, ending in a single broad, spatulate, fin-like lobe; 
endites of feet much broader and more rounded than in Branchipodine ; 
frontal appendage of male tree-like; of female, long and clavate, simple. 
“Ya 
THAMNOCEPHALUS* Packard. 
Thamnocephalus Pack., Bull. Hayden’s U. S. Geol. and Geogr. Survey Territories, iii, 
175. April 9, 1277. 
Male.—Claspers (second antenne) with the basal joint short, the upper 
* Odurv ot, shrubby, bushy; xepads, head. . 
