24 PROCEEDINGS OF THE ACADEMY OF [1887. 



larval form of this genus. Its more evident characters may be 

 summed up as follows : 

 Tsenia loliginis. 



Head unarmed, without rostellum, quadrilobate, continuous 

 with the neck, which is variably long and narrow or short and 

 irregularly contracted and expanded, and is constricted from the 

 body. Lobes of the head elliptical, contractile and expansile 

 and becoming variably folded or corrugated, furnished each at 

 the upper pole with a hemispherical bothria. Body about as 

 long as the head and neck, extensile and contractile, obconic or 

 obovate, compressed, acute posteriorly, unsegmented. No inte- 

 rior organs visible except a vessel along the sides of the neck and 

 encircling the lobes of the head. Color white. Length to about 

 half an inch ; width about 1 mm. Dr. H. C. Chapman informed 

 me that he had previously observed this parasite in the squid. 



Monostomum obscurum. 



Elongated elliptical, flattened, obtusely angular in front, obtusely 

 rounded behind. Oral and genital or other apertures scarcely 

 distinguishable. Length; 4 to 8 lines ; width 1 line. 



Numerous specimens in the stomach of a Jew-fish, Megalops 

 thrissoides. Collection of the Army Medical Museum, Washington. 



Distomum Aquilse. 



Spatulate, cochleariform, widest behind, obtuse at both ends; 

 mouth circular unarmed; acetabulum sessile, about as large as 

 the mouth. Length, 3 lines; width in front, i a line; behind, I of 

 a line. Two specimens from the trachea of the Bald Eagle, 

 Halicetus leucocephalus. Collection of the Army Medical Meseum. 

 Distomum hispidum Abildgaard. 



Body much attenuated in advance, covered with minute 

 recurved spines, which become obsolete at the back part. Head 

 with a pair of alate appendages covered with stronger recurved 

 spines, and a small group in the intervals before and behind. 

 Mass of eggs giving the axis of the body behind a red appear- 

 ance. Ova oval, 00"4 mm. long, 00*24 mm. broad. 



Numerous specimens, about 4 lines long by 0'5 mm. where 

 widest behind. From the intestine of the Sturgeon, Accipenser 

 sturio, of the Delaware River, at Philadelphia. 

 Nitzschia elegans Baer. 



Several specimens of this leech, four lines long, were taken 

 from the gills of the same sturgeon. 



