RESEARCHES IN HELMINTHOLOGY AND PARASITOLOGY. 53 



aerial animals ; and both methods are frequent in aquatic animals, 

 because in the latter case the water affords a good vehicle for the 

 approach of the parasites to any part of the body of the animals to 

 be infected. 



As hemipterous insects suck the juices only of plants or animals, 

 through a delicate proboscis, they are placed under circumstances 

 the most favorable of all animals to avoid taking in with their food, 

 ova, spores, or developed animals and plants of a parasitic character, 

 whilst insects like Passa/ns, crickets, etc. , or Juliis among myriapoda, 

 from their eating decaying substances, swallowing large morsels of 

 such food, are very apt to take in parasites. 



Frequently I have detected adhering to insects and annelida, while 

 living, cryptogamic sporules, which, under favorable circumstances, 

 before or after the death of the animal, undergo development into 

 the perfect plant. House-flies, and especially earth-worms, are very 

 liable to the growth of Achlya upon them, and sometimes I have 

 even detected the growth of the latter upon the surface of earth- 

 worms still living. 



[June, 1851. No. 79. See Bibliography.] 



HELMINTHOLOGICAL CONTRIBUTIONS NO. 2. 



ASPIDOGASTER, B.\ER. 



Aspidogastcr coiichicola, Baer. Act. Acad. Nat. Cur., T. 13, p. 

 527 ; Dujardin, Hist. Nat. des Helm., p. 324; Diesing, Syst. Helm., 

 vol. I, p. 414. 



Body oval, posteriorly obtusely rounded ; color yellowish white. 

 Neck translucent, cylindric ; mouth terminal, large, surrounded by 

 a thick, contractile lip. Lateral margin of ventral disk crenate. 



MeasurcDioits at rest. — Length ^2 to 4-5ths of a line by i/|th to \iA 

 of a line broad. Neck /<(th length of body b}^ i-gth line in breadth. 

 CEsophageal bulb longitudinally oval, r-i66th inch long by i -285th 

 inch broad. Ovum oval, i-333d to i -285th inch long by i -666th to 

 I -500th inch broad. 



Measurements in crr//^,'/.— Length i to 1^/2 lines by i-5tli to 54^th 

 line broad. Neck may elongate to one-half length of body by 

 I -200th in breadth. Lip may expand into a circular disk or be 

 elongated into a triangular rostrum. 



Hab. — Found in the pericardial cavity of Uuio piirpureus, U. na- 

 sutus, U. radiatus, U. eariosns, and Anadonta marginata. 



