40 CEYLON PEARL OYSTER REPORT. 



varies with the state of the contraction or expansion of the body. The cuticle is 

 finely striated. The reproductive pores are alternate, but rather irregularly so, two 

 consecutively left or right sometimes appearing. 



Habitat : Aetobatis narinari, in the spiral intestine. 



Kystocephalus, n. gen. 



Head bladder-like, with four small suckers and a myzorhynchus which is partially 

 covered by a membrane. Proglottides with very salient posterior borders, most 

 of them much broader than long. Lips of reproductive pores, which are irregularly 

 alternate, very prominent. 



Kystocephalus translucens, n. sp. Plate I., figs. 11 and 12. 



The two specimens of this worm at our disposal measured, respectively, 10 millims. 

 and 35 millims., yet each appeared to end in ripe proglottides. 



The head and the thicker part of the body measured 0'4 millim. in breadth. The 

 head is a curiously bladder-like concern, which takes little stain and bears four 

 very small spherical suckers. There seems to be a myzorhynchus, surrounded and 

 half enclosed in a circular membrane. The membrane, however, has a central circular 

 aperture through which the myzorhynchus protrudes. Immediately behind the head 

 the proglottides appear, and for about one half the body-length they are considerably 

 broader than long ; they then become square, and the last five or six are longer than 

 broad. The posterior end of each proglottis widens out like the walls of a funnel 

 and overlaps the anterior end of the succeeding proglottis to a much greater extent 

 than is usual, so as to sometimes cover a third of the hinder proglottis. At least this 

 is the case in one of our specimens ; in the other this salient edge was curled back 

 like the brim of a top-hat. The genital orifices are lateral and in the posterior 

 proglottides have very prominent lips ; they are irregularly alternate, usually two 

 or three on one side and then three or four on the other. 



This form seems to be not far removed from the genera Tylocephalum and 

 Cephalobothrium, but it is marked off by quite definite features. 



Habitat : Aetobatis narinari, in the intestine. 



Myzocephalus, n. gen. 



" Head" with four slipper-shaped bothridia each divided by a horizontal partition 

 into two areolas. " Head " surrounded and smothered in four most voluminous and 

 crumpled folds like the bothridia of Anthobothrium. Proglottides barrel-shaped. 

 Reproductive pores irregularly alternate. Cuticle finely ringed. 



Myzocephalus narinari, n. sp. Plate I., figs. 13, 13a, 14, 15, 16a, b, c. 



This remarkable form reminds one of an Anthobothrium which has enormously 

 developed and crumpled up its bothridia, as in Phyllobothrium, and which retains a 



