M. Turner ]:39 



The blade is of moderate curvature in all the large hooks. The axis 

 of the handle in the Coenurus of the rat, in C. cerebralis and in C. serialis 

 is straight. In all the dorsal and ventral margins of the handle are practi- 

 cally parallel and somewhat sinuous. The curves of these margins are 

 large in C. serialis, and very slight in the Coenurus of the rat. 



The handles of the large hooks of the Coenurus of the rat, of C. cere- 

 bralis and of C. serialis, all taper distally, but very slightly so in the two 

 first and more so in the last. In all the distal end of the handle of the 

 large hooks tends to turn dorsally. In C. cerebralis this dorsal bend is 

 usually scarcely perceptible; in C. serialis it is more pronounced, while in 

 the Coenurus of the rat, it is very marked in many of the hooks. 



The proportion of the height of the blade to the length of the handle 

 in the large hooks of one Coenurus is not the same as that of the hooks 

 of another Coenurus. In all the large hooks from the Coenurus of the rat 

 the handle is noticeably longer than the blade, which gives the handle 

 a slender appearance. In C. serialis the handle may be somewhat longer 

 than the blade though usually they are about equal. In C. cerebralis the 

 blade is longer than the handle so that the handle appears strong and thick. 



A notch is frequently present on the dorsal margin of the handle of the 

 large hook of (J. cerebralis and is often seen in some hooks of the Coenurus 

 of the rat. 



One of the chief features by which these large hooks may be distin- 

 guished is the shape in lateral view of the guards. In the hooks of the 

 Coenurus of the rat the guard is triangular with its maximum diameter 

 at the base and usually with a pointed distal end. The guard of C. cere- 

 bralis is practically cylindrical for some way out from its base and then 

 tapers sharply to its free extremity. Its greatest diameter is usually just 

 before the guard begins to taper. 



In the majority of the large hooks of C. serialis the guard is almost 

 cylindrical with a blunt rounded tip. 



In C. cerebralis and C. serialis the core of the hook does not enter the 

 guard but in the hooks of the Coenurus of the rat it penetrates the broad 

 base of the guard for a short way. 



The axes of the guard and the handle of the large hooks of each Coe- 

 nurus meet at about 90°. 



In my material the small hooks of the Coenurus from the rat are from 

 90 fi to 105 /z in length: those of C. cerebralis are from 95 fi to ISO/a 

 (Hall gives 90 ^u, to 130 /a) and those of C. serialis from 90 fx to 100 /i (Hall- 

 gives 78 /i to 120/x). So that the small hooks of C. cerebralis are the 

 longest. 



10—2 



