110 
PROCEEDINGS OF THE ACADEMY OP 
medianus styliformis, gracilis, setosus ; dentes laterales acuti. Chelopoda 
foeminae gracilia ; mero ad apicem dentigero ; manu gracili ; digitis palmam 
longitudine adaequantibus. Pedes ambulatorii graoillimi, fragiles, subtiliter 
setosi, ut in R. messori dentigeri, dentibus acutioribus ; dactjlis longioribns, 
gracillioribus, ultimi paris quam reliquis magis curvatis. 9 Carapacis long. 
0-19 ; lat. 0-175 poll. 
Ilab. — In portu ' ' Hong Kong. ' ' 
Contributions to Helminthology. 
BY JOSEPH LETDY, M. D. 
CoTYLASPis, Leidy. 
Body curved infnndibuliform, anteriorly cylindro-conical, posteriorly ex- 
panding into a subcircular or oval ventral disk with numerous acetabnla 
arranged in a triple series. Month infero-terminal, with a prominent lapper 
lip, and protractile into a cup- or disk-like acetabulum. Intestinal apparatus 
as in Aspidogaster. Eyes two, distinct, black, situated on each side of the 
head. Grenerative apertures inferior, between the head and ventral disk. 
CoTYLASPis msiGNis, Leidy. Proc. Nat. Sc. 1857, 18. 
Translucent white or pink white. Upper lip snout-like, conical. Ventral 
disk crenate at the margin ; acetabula 29, oblong quadrate, the outer rows 
continuous in front and behind so as to form a circle. Length from J to 1 line : 
ventral disk from ;i to |^ a line in diameter. 
Habitation. — Found adhering to the outer surface of the renal organ, and the 
upper margin of the foot, within the cleft of the upper branchial cavity of 
Anodonta Jiuviatilis and A. lacustris. 
Remarks. — This curious parasite, though allied to Aspidogaster conchicola, is 
certainly distinct ; and it never occupies the locality of the latter, which also 
is found in the pericardium of Anodonta Jiuviatilis and A. lacustris. It is an 
interesting fact that in accordance with its exterior position Cotylaspis pos- 
sesses well developed eyes, while the imprisoned Aspidogaster is hlind. It has 
occurred to me that perhaps these two genera may represent two different 
stages of existence of the same animal. 
Rhopalocerca tardigrada, Diesing. 
Attached to the mantle of Anodonta Jiuviatilis ; specimens also obtained by 
Mr. Lea from A. lacustr s. 
Heterostomum echinatum, Filippi. 
From oviduct of Paludina decisa. Quite common. 
Cercaria agilis, Leidy. 
Body, when elongated, narrowed pyriform ; when shortened, obcordate ; 
posteriorly emarginate ; anteriorly triangular. Mouth acetabuliform, large, 
globular. Acetabulum little larger than the mouth, nearly central in the 
shortened condition of the body, at the posterior third of the latter when 
elongated. Sporocerca as long as the body, long clavate, trans versely plicated - 
Color white. 
Exceedingly active ; found in the Delaware river, quite commonly in com- 
pany with Planorbis, Paludina, and Lymnea. 
DiPLOSTOMUM GRANDE, Diesing. 
Head oblong oval, a little oblique ; margin entire, inflated. Mouth small, 
round. Male aperture small, round ; female aperture large, prominent, longi- 
tudinally oval. Body conical. Ovaries dusky yellowish. Length 1 line : 
breadth \ line ; head | line long ; body | line long. 
Twenty specimens were obtained from the intestines of Strix nivea. 
MoNOSTOMUM AFFiNE, Leidy. 
Body spatulate, narrowest anteriorly, flat ; posterior end obtuse, with an 
excretory orifice communicating with a well marked canal traceable as far for- 
ward as the commencement of the oviduct. Mouth round, oral acetabulum 
[April 
