358 ON THE CEYLON PEARL-OYSTER. 
Kig. 58. Tylocephaium ludificans, sp.n. Type. Section through an example in the 
tissues ot the Ceylon Pearl-Oyster in Professor Herdman’s collection. 
Slide 94 of Professor Herdman’s series. a., armature of collar. This shows 
the myzorhynchus of “ Tylocephalum” form, due to the posterior face 
(m.p.) being contracted and its surface thrown into folds and the anterior 
tace (m.a.) stretched. Compare the adult 7'ylocephala in figs 61 & 62, 
and also the species shown in fig. 65. X 70. 
Fig. 59. Section through another example of the same species, showing the “ Cepha- 
lobothrium’’-form of myzorhynchus; here the posterior surface of the 
myzorhynehus (m.p.) is tense, and its anterior surface (7.a.) is thrown into 
folds. a, armature of collar. (Compare theadult worm in fig. 66.) X 70. 
Fig. 60. An adult worm, which may be the adult of Tylocephalum ludificans, 
from the spiral intestine of Aétobatis narinari. X 6. From Dr. Shipley’s 
collection. 
Puate XLVIL. 
Fig. 61. The head of the worm shown in fig. 60, viewed as a transparent object. 
m., myzorhynchus ; s,s’, s’’, three of the four marginal suckers; a., armature 
of collar ; seg., first proglottides. XX 70. 
Fig. 62. The same, in section; letters as above. XX 70. 
Fig. 63. Armature of collar of same, about point @ in fig. 62. XX 1000. 
Fig. 64, Penultimate segment of same. 
Fig. 65. Head of Tylocephalum uarnak from Trygon uarnak. From a slide in 
Dr. Shipley’s collection. my., myzorhynchus, which here is fully protruded ; 
ma., anterior face of same; mp., posterior face; s, s’, s’’, s’’’, the four 
marginal suckers. X 45. 
Fig. 66. Head of Cephalobothrium aétobatides from Aétobatis narinari. From a 
specimen in Dr. Shipley’s collection. Letters as above. X 70. 
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