RESEARCHES IN HELMINTHOLOGY AND PARASITOLOGY, 73 



about their middle had already developed respiratory fovese and 

 were slightly indented preparatory to division before the first pair 

 were separated. 



1. MicrostoDiiini {EiistoiiiuDi) Philadclphicum, Leidy. 



Body linear, slightly attenuated posteriorly ; head conoidal, with 

 the apex surmounted by a small oval papilla ; tail obtusely rounded. 

 Respiratory fovea sub-hemispherical, placed at the base of the cone 

 of the head. Mouth oval, protractile ; oesophagus keg-shaped, in- 

 testine narrowed, cylindroid, dilated at the commencement ; color- 

 less, translucent, vibrillated, increasing by transverse segmentation, 

 always observed in the process of forming two segments. 



Ivength 2-5ths line by i -500th inch broad. 



Habitation. — Found in the water of marshes and ditches in the 

 neighborhood of Philadelphia. 



2. Microstonuim {Eustomum) Variahile, Leid}'. 



Body broad, linear ; anteriorly and posteriorly obtusel}- rounded. 

 Respiratory fovea, longitudinally oval, lateral. Intestine very broad ; 

 colorless, increasing by twos. 



lycngth from i-8oth to i-24th of an inch by i -Sooth to i -400th 

 inch broad. 



Habitation. — With the preceding. 



3. Microstomiun {Ejcstonnim) Caudatuni , L,eidy. 



Body long, narrow, linear ; anteriorly obtusely rounded, posteriorly 

 ending in a narrow, blunt, elevated tail i -400th inch long from the 

 position of the anus ; increasing b}* twos, the tail of the anterior 

 segments projecting above and its whole length posterior to the head 

 of the succeeding segment. 



Length 3-4ths to 1^4 lines ; breadth i-30oth to i-250th inch. 



Habitation. — With the preceding. 



Rhynchodemiis Sylvaticiis, Leidy. Pr. A. N. S.,v, 289. Error of 

 reference. 



Planaria sylvatica, Leidy. lb., 241. 



Stylaria Fossularis, Leidy. lb.. 287. A number of individuals in 

 a state of segmentation, from which the species was first described, 

 preserved alone in a glass vessel with some confervse ; upon the oc- 

 currence of cold weather passed into the perfect condition as follows : 



Body long, cylindroid, hyaline, permitting the ash-colored or 

 yellowish intestine to be seen through the integument, divided into 

 from 50 to 65 annulations, furnished with a distinct girdle posterior 

 to the third annulus from the mouth, which extends the breadth of 

 three annuli. Podal hooks in fasciculi of 10 to 12. Setae commenc- 



