43 CANTONj ON PARASITIC OVA. 



groups, there are five, eight, or sometimes ten, collected to- 

 gether. 



In all the eyes examined, with the exception of those of 

 the sixth turtle, I discovered a second form of ovum, not dif- 

 fering, however, in any material degree, from that already 

 described. 



The body is elongated, but not so swollen as in the pre- 

 ceding variety, though it is still unequally ovate. The 

 shorter filament, which terminates one extremity, is less 

 regularly infundibuliform ; its thinnest portion is rather sud- 

 denly bent at an acute or right angle to the body, and ends 

 in two hooks, joined by their convexities. From the oppo- 

 site portion of the body the suctorial filament passes, and is, 

 relatively to the corresponding part in the first-mentioned 

 oVa, longer and more thread-like ; slightly funnel-shaped at 

 its commencement, it soon contracts, and, after a more or 

 ■ less flexuous course, ends by a rather sudden expansion into 

 a flattened disc. 



These ova are exceedingly few in number, and are generally 

 smaller than those first described; they are, for the most 

 part, found solitary : I presume them to be the same as those 

 previously mentioned, only in an earlier stage of development. 

 Dr. Spencer Cobbold has obligingly examined my speci- 

 mens, and I am indebted to him for the favour of the following 

 communication : — '' After a careful examination, I have ar- 

 rived at the conclusion that the foreign cystic bodies adherent 

 to the conjunctiva are the ova of an ectozoon, the latter 

 being parasitic, either upon the turtle itself, or upon some 

 crustaceous epizoon likewise infesting the turtle. 



" These ova difl'er in appearance from any I have hitherto 

 encountered, and are especially interesting in the circum- 

 stance of their presenting filamentary appendages at both 

 ends. The hook-like filament is, probably, distiuctive of the 

 species of parasite to which the ova may be referred. 



"The eggs of various forms of entozoa, and also in the 

 allied ectozoa, display filamentary appendages at both ends 

 of the chitinous shell- capsules ; these processes generally re- 



