294 Part ITI.— Ninth Annual Report 
The sculpture of this exceedingly small species is like that of no other 
Lyncetd. It consists of bold and obliquely curved striz, and not merely 
impressed lines, which impart a beautifully fluted appearance to the shell 
when the light strikes across the strie. My specimens differ somewhat 
from that figured by Norman and Brady in the work cited, in the rostrum 
being less curved—being in fact nearly straight—whereas the figure shows 
the rostrum curving inwards considerably. My specimens agree better 
with the figure of A. pygmcea in Herrick’s report. It seems to be a some- 
what rare species. 
Peracantha, Baird. 
Peracantha truncata (Miiller). 
1781. Lynceus truncatus, Miller, Entomostraca, p. 75, pl. ii. figs. 4-6. 
1850. Peracantha truncata, Baird, Brit. Entom., p. 136, pl. xvi. fig. 1. 
1867. Lynceus truncatus, Nor. and Brady, loc. cit., p. 387, pl. xxi. fig. 9. 
1884. Pleuroxus truncata, Herrick, loc. cit., p. 112. 
This is one of the more distinctly characterised species, the posterior 
extremity of the carapace is subtruncate and ‘‘armed all along the edge 
with a series of large tooth-like processes, the hindermost of which are 
directed backwards; surface of shell divergently striated.” I have followed 
Norman in retaining Baird’s generic name, Peracantha.* 
Pleuroxus, Baird. 
Plewroxus levis, G. O. Sars. 
1844. Lynceus trigonellus, Zaddach, Syn. Crust. Pruss. Prod., p. 
1861. Plewroxus levis, G. O. Sars, ‘Om. de i Omeg. af Christi. iw crear Clad., 
p. 22. 
1867. Lynceus levis, Nor. and Brady, Joc. cit., p. 889, pl. xviii. fig. 54 pli xt 
fig. 14 
g. 14. 
1884, Pleuroxus hastatus, Herrick, loc. cit., p. 108, pl. i. fig. xvi. 
This species may be distinguished from the others by the form of the 
post-abdomen, which narrows gradually towards the claws. The claws 
are furnished with two basal spines. With alow power of the microscope 
the carapace appears faintly costate, but under a moderately high power 
(4 inch) the surface is seen to be reticulate, besides being finely striate 
longitudinally. 
Plewroxus trigonellus (Miiller). 
1776. Lynceus trigonellus, Miller, Zool. Dan. Prod. No. 2395. 
1850. Plewroxus trigonellus, Baird, Brit. Entom., p. 134, pl. xvii. fig. 3 (fem.). 
1850. Plewroxus hamatus, idem ibidem, p. 136, pl. xvii. fig. 5 (mas. ). 
1867. Lynceus trigonellus, Nor. and Brady, loc. cit., p. 391, pl. xxi. hg. te 
1884, Plewroxus trigonellus, Herrick, loc. cit., p. 108. 
A widely distributed species, but seldom very abundant. The post- 
abdominal claws are furnished with one basal spine. 
Pleuroxus uncinatus, Baird. 
1850. Plewroxus wncinatus, Baird, Brit. Entom., p. 185, pl. xvii. fig. 
1867. Lynceus payee Nor. and Brady, Joc. cit. A108 393, pl. xviii. fig. 9; pl. 
DOG TCE NL 
1884, SERN Herrick, loc. cit., p. 114. 
This seems to be widely distributed though not very common. It varies 
a good deal in the shell sculpture. ‘There are also slight modifications in 
the form of the carapace ; the greater number of our specimens have the 
sostrum more closely appressed to the shell than in those figured by 
Norman and Brady, and in this respect they agree more closely with 
Baird’s figure. The post-abdomen is similar to Norman and Brady’s 
figure. 
* See Museum Normanianum, pt. iii. (1886). 
