T. B. ROSSETEK ON CYSTICERCUS QUADRICURVATUS. 339 



veiy symmetrical curves, two concave and two convex. The pos- 

 terior root commences with a very sharp point, then gracefully 

 curves inwards (concave) and outwards (convex), again be- 

 coming concave opposite the anterior and convex to form the 

 claw of the hook, which also terminates with a sharp point. 

 Tlie claw is not unduly or sharply curved, and a parallel line 

 can be drawn from tlie tip of the posterior root to the termina- 

 tion of the claw. The facial portion of the root, where the 

 anterior root commences, thickens considerably posteriorly, and, 

 continuing to do so, forms the root. But this facial portion of 

 the root is not sharp or rounded, but squares oft' at a right 

 angle, the anterior portion gracefully curving inwards to form 

 the claw (see Fig. 3). 



The hooks are placed on the rostrum back to back (see Fig. 

 2), a remarkable circumstance, so that when in its mature con- 

 dition it is in the intestine of its final host it buries its scclex, 

 together with its elongated proboscis and rostrum, in the villi 

 of the mucous membrane of the duodenum. The claw has to be 

 raised to a given angle to give the hooks a firm grip of the 

 tissue, so as to prevent expulsion during the passage of the 

 triturated aliment from the gizzard, which, together with the 

 digestive juices, is poured into the duodenum. This would cause 

 the hooks, as far as their claw is concerned, to be considerably 

 elevated. To enable them to be so the radial muscles of the 

 bulb of the rostrum, which not only encircle the rostrum but 

 are likewise attached to the posterior root, are considerably 

 expanded. This expansion is brought about by the contraction 

 of the longitudinal muscles, which run the whole length of the 

 proboscis down into the scolex, from whence the momentum 

 would be received, and which, like the radial muscles, are 

 attached to the posterior root ; the concave portion over which 

 the longitudinal muscles lap rests on the base or crown of the 

 bulb of the rostrum. This action of the longitudinal muscles 

 must, in consequence of the formation of the root, cause a de- 

 pression of the crown of the rostrum. The depth of this depres- 

 sion depends on the elevation of the hooks, and when they are 

 fully elevated the radial muscles are stretched to their utmost ; 

 on the contrar}^, when they are depressed the muscles are 

 brought back to their normal position. 



The question will naturally be asked — How, if an adult 



