54 CEYLON PEARL OYSTER REPORT. 



schcepfii. The present species is from the intestine of Balistes sp., the File- or Trigger- 

 fish found on the Ceylon pearl banks (Plate, fig. 11). The distoma is characterised 

 as follows : Length 5 millims. ; perfectly smooth skin ; anterior sucker almost 

 globular, with a relatively small mouth ; the pharynx does not directly abut on the 

 anterior sucker ; oesophagus wide ; digestive caeca reach to posterior end ; yolk- 

 glands extraordinarily prominent, arranged in 2 rows, one on each side and behind 

 the testes ; the shell glands and receptaculum seminis not easy to distinguish, but 

 they lie anterior to the ovary ; the termination of the vas deferens is apparently 

 eversible and is probably used as a penis ; a definite penis is absent ; numerous 

 glands surround the terminal parts of both the male and the female ducts. 



This species seems to differ from the Distoma pollens of RUDOLPHI in the facts 

 (i.) that the ventral sucker is not twice the size of the oral, (ii.) the aperture of the 

 ventral sucker is rounded and is not a transverse slit, (iii.) the ovary is not globular, 

 (iv.) the yolk-glands are prominent and arranged in two rows. 



Distomum richiardii, LOPEZ. 



Many specimens of this elegant little Trematode were taken from the perivisceral 

 cavity of Rhinodon typicus. The species has recently been described by MONTICELLI,* 

 who has found it in the body-cavity of Acanthias vulgaris and more rarely in 

 Mustelus vulgaris and Myliobatis aquila, in the Bay of Naples. 



III. NEMATODA. 



Cheiracanthus spinosissimus, u. sp. Plate, figs. 12 and 13. 



Length 137 millims., breadth 0'45 millim. ; oesophagus -$, and the conical tail, 

 which is round quite at the end, is 3^- of the whole body-length ; cuticle 0'022 millim. 

 thick, tough, transversely wrinkled ; head end rounded like the mouth of a Turkish 

 pipe (Plate, fig. 12); four tongue-like projections pointing backwards in the inter- 

 mediate areas ; 30 to 33 transverse rings, each consisting of some hundreds of spines ; 

 six lips around the mouth ; four neck glands of f to f the length of the oasophagus, in 

 front these are thin, with two swellings, but they thicken behind and contain spiral 

 muscles ; intestine dark brown ; the tail has on each side two prse-anal and four post- 

 anal papillae, arranged as shown in fig. 13 ; the papillae in outline resemble a skittle ; 

 cirri equal and 07 millim. long. 



This Nematode was obtained from Myliobatis aquila, in the Gulf of Manaar. 



This above definition has been furnished by Dr. VON LINSTOW, who kindly 

 undertook to investigate the Cheiracanthus. He adds that this new species differs 

 from C. unicinctus both in its head and in its neck glands. 



* 'Zool. Juhrb. Syst.,' vi., Supplement, 



