CESTODE AND NEMATODE PARASITES. 47 



myzorhynchus or "head." The largest of our specimens measured 25 millims. in 

 length. The head with its ruff-like bothridia measures 2 millims. across and the 

 posterior ripe proglottides measure 1 millim. transversely. The anterior end consists 

 of a head which bears four slipper-shaped bothridia each divided by a horizontal 

 ridge into two areolas. They are very mobile. In life the head is very contractile 

 and readily alters its shape (figs. 16a, b, c). Its anterior end is rounded. The water 

 vascular canals penetrate the head and anastomose there, branches are also given off 

 into the " ruff." During life the puckered bothridia were continually undergoing 

 changes of form and the whole mass was in constant motion and transformation. 

 The ruff is formed of four immensely crumpled lateral extensions which branch all 

 together and completely hide the head and give the anterior end of the body the 

 appearance of a cauliflower. These four extensions are borne on four stalks which are 

 equally immersed in their voluminous folds. It needs but an extension of the 

 so-called bothridia of Anthobothrium to produce this ruff, but if the extensions are 

 morphologically bothridia, then in this worm we have a double set of bothridia, one 

 in the head, the other forming the ruff. The excretory tubes on each side extend to 

 the end of the myzorhynchus, and then double back. 



There is no neck, the transverse divisions beginning immediately after the insertions 

 of the ruff. The line between the proglottides is straight, and except faintly at the 

 anterior end of the body there is no trace of overlapping. The cuticle is finely ringed. 

 The proglottides are barrel-shaped, arching out at each side. The first differentiation 

 which arises in the growing proglottides is the appearance of the scattered testes, and 

 almost at the same time the primordium of the uterus and genital ducts arise. The 

 uterus even in our ripest specimens remains unbranched. The complex of the ovary 

 and shell gland lies posteriorly. The openings of the genital duct are irregularly 

 alternate, perhaps 4 on the right side, 1 on the left ; 5 on the right, 3 on the left, and 

 so on. 



Habitat : The spiral intestine of Aetobatis narinari taken off Dutch Bay, Ceylon. 

 These Cestodes came from the specimen B mentioned on page 44. 



Myzophyllobothrium, n. gen. 



Long worms, some 80 millims. in extent. Head with myzorhynchus with four 

 suckers, four bothridia, sessile, with smooth edges and a thickening (? small sucker) at 

 the apex. No neck. Proglottides never overhanging, with anteriorly straight sides. 

 Red pigment at base of head apparently associated with water vascular system. 



Myzophyllobothrium rubrum, n. sp. Plate I., figs. 17 and 18, and Plate II., 

 figs. 19 to 21. 



This curious worm, taken from the intestine of Aetobatis narinari, belongs to the 

 order Tetraphyllidea,* CARUS, and to the family Phyllobothriidae, but it seems to us to 



* BRONX'S ' Thierreich.' " Cestoda," by M. BRAUN. 



