390 PROCEEDINGS OF THE NATIONAL MUSEUM VOL. 113 
sexual dimorphism, and their mode of reproduction (the eggs are 
deposited freely). As in the case of the crustaceans Bathynella, 
Niphargus, and Microparasellus, and the polychaete Troglochaetus, 
Parastenocaris reflects the amount of research on subterranean waters. 
During the past 30 years this research has greatly increased. Although 
the type of the genus, P. brevipes, was not described until 1913 (Kessler, 
1913), about 70 species are now known. It would not be surprising 
if this number should eventually exceed 100, inasmuch as the study of 
tropical interstitial biotopes is in its infancy. 
It is of considerable interest that until about 1950, tropical Para- 
stenocaridae were found only in water in the interstices of plants, 
whereas in Europe the genus Parastenocaris occurs almost exclusively 
in subterranean biotopes. Of the European species, only P. brevipes 
is known from both surface and subterranean situations. In recent 
years, however, several new subterranean species of Parastenocaris 
have been discovered from Africa and South America (Chappuis, 1952; 
1954a; Noodt, 1955). 
The following abbreviations are used in the descriptions and illustra- 
tions that follow: 
A.l Antennule P.1-P.5 Thoracic legs 
A.2 Antenna Exp. Exopodite 
Md Mandible Enp. Endopodite 
Mx Maxillule Benp. Base-endopodite 
Mxl Maxilla Fu Furca 
Mxp Maxilliped 
We wish to acknowledge the aid received from Conselho Nacional 
de Pesquisas, Rio de Janeiro. 
Genus Parastenocaris Kessler, 1913 
Parastenocaris brasilibathynellae, new species 
FIGuRE 1 
Female: Body cylindrical, cephalothorax considerably larger than 
any of the following segments, twice as long as third thoracic seg- 
ment; operculum concave centrally, well chitinized, without orna- 
mentation. Size varies according to method of fixation, normally 
about 10 times longer than wide. Body segments without ornamen- 
tation or other differentiations. Rostrum lacking. Furcal branches 
about 3 times longer than wide; the terminal bristles reduced to 
spines (sexual dimorphism), as in Parastenocaris hexacantha Kiefer 
1936, oval as seen from side, in contradistinction to male. Furca of 
the same length in both sexes, always a little shorter than the last 
abdominal segment (for details, consult figures). Mandibula a 
very small chewing plate, divided. Maxillule small and with rela- 
tively strong bristles. Maxilliped easily demonstrable, prehensile. 
