284 DR. H. LYSTER JAMESON ON 
tT Tylocephalum dierama (Report V. p. 59). Intestine of Mylio- 
batis maculata. Diameter of head *6 mm. 
Tylocephalum kuhli (Report V. p. 72). Intestine of Zrygon 
kuhli. Head apparently about *5 mm. in diameter, 
tT ylocephalum uarnak (Report V.p. 76). Intestine of 7rygon 
uarnak and Trygon walga. Head apparently about 1 mm. 
in diameter. 
*?Cephalobothrium actobatidis (Report V. p. 44). Spiral valve 
of Aétobatis narinari. Diameter of head ‘5 mm. 
*tAKystocephalus translucens (Report V. p. 46). Intestine of 
Aétobatis narinari. Diameter of head ‘4 mm. 
*Eniochobothrium gracile (Report V. p. 64). Intestine of 
Rhinoptera javanica, Head appears to measure about 
‘4 mm. in diameter. 
*rTiarabothrium javanicum (Report V. p. 67). Intestine of 
Rhinoptera javanica, Head | mm. broad. 
To these may be added two forms described by Mr. Southwell 
(41 a), viz. :— 
Cephalobothrium abruptum, trom the spiral valve of Pteroplatea 
micrura. Head 1:2 mm. broad. 
Cephalobothrium variabile, from the intestine of Pristes cuspi- 
datus. Head 1 mm. broad. 
The forms marked * oceur in hosts which are known to feed 
on pearl-oysters. Those marked + I have been able to examine 
through the courtesy of Dr. Shipley. It is impossible not to be 
struck with the resemblance between the heads of some of the 
above species and the parasites which Herdman associates with 
pearl-formation. Compare, for example, the head of Cephalo- 
Lothrium aétobatidis, figured in Part V.(Cestoda) plate 1. figs. 1-4, 
with some of the figures of 7'ylocephalum ludificans in the chapter 
on Pearl-Production (Part V. Pearl-Production, plate ii.) or 
the heads of 7'ylocephala (Tetragonocephala) as figured on the plate 
of Part ITI. (Parasites), and in thearticle on Cestodes in Part V. 
(pl. v. figs. 76-7), with some of the figures in the article on the 
parasites of the Pearl-Oyster in Part II. Or, again, compare the 
section of 7'ylocephalum ludificans from the pearl-oyster shown 
on Pl. XLVI. fig. 58, with the head of 7. warnak, Pl. XLVIL. 
fig. 65, drawn from one of Dr. Shipley’s slides, asa representative 
of the genus T'ylocephalum, taking into account the difference 
that in the former the myzorhynchus is withdrawn within the 
collar, whereas in the latter it is fully protruded. Or compare 
Pl. XLVI. fig. 59, a section of 7. ludificans from the pear]- 
oyster, with the head of Cephalobothrium aétobatidis, from one of 
Dr. Shipley’s slides shown on Pl. XLVILI. fig. 66. Similarly, 
compare figs. 58 & 59 with the worm shown in figs. 61 & 62 on 
Pl. XLVIT., also from A étobatis narinari (the final host of Seurat’s 
larva) =. Ithink the worm shown in figs. 60-64 is quite probably 
t It is strange that the oyster-eating habits of this Ray do not seem to have 
heen recorded in these Cevlon researches. 
[26] 
