802 LAEVAL CESTODE PARASITES OF FTSHES—TJXTOX. 



List of specimens. 



I leprotluee, with the omissiou of many details, the description of this 

 species contained in the article in the "American ^Naturalist.'' ' 



Cysts like this — i. e., containing an embryo rhynchobothrium, either 

 of the same or kindred forms — are common in most of the teleostei, 

 and are occasionally found in selachians. In the specimen under con- 

 sideration (a cyst from the peritoneum of the bluefish) the length was 

 12 mm., and the breadth in the widest part G mm. The cyst was clavate, 

 its Malls thin, transparent, and delicate, with yellow granular i^atches 

 at the larger end. It was easily separable into two hyaline connective- 

 tissue layers, the outer thicker than the inner. 



The blastocyst when released from its capsular envelope was white 

 and opaque, but became translucent, with a faint bluish tinge when 

 compressed and viewed by transmitted light. Tlie form, while some- 

 what variable, is usually club-shaped, much larger at one end than 

 the other, the larger end blunt and rounded. When placed in sea 

 water, it continues in a state of activity for hours. There is no decided 

 locomotion, but a continuous series of movements, consisting of alter- 

 nate contraction and extension of different i)arts of the sac-like mass 

 and feeble lateral movements of the smaller end. In this condition 

 the appearance of the blastocyst is that of a thick-walled sac, the walls 

 of which are made up of granular protoplasm, with a thin investing 

 membrane, and tilled with clear, highly refractile globular masses. 

 When slight pressure is applied, the embryo may be seen lying in a 

 loose coil in the larger end of the blastocyst. Two sinuous vessels, one 

 on each side, can be plainly seen lying along each side. These unite in 

 the median line at the smaller end. At the larger end they appear to 

 be lost in the common i)arenchyma. In the immediate vicinity of the 

 embryo the blastocyst is more transparent than in other parts, and the 



February, 1887, pp. 199, pi. x. 



