260 CEYLON MARINE BIOLOGICAL REPORTS.' 



of PlaciiiM placenla is the same as in the pearl oyster, but tlio occurrence of tlxe adult in a Trygon was 

 surprising, as tlie adult form is so very rarely found. 



A few of the genera, and many of the species, of cestodes described by Shipley and Hornell from 

 the pearl banks have not been obtained by me. 



I append to this paper a full list of the cestodes obtained by me from the pearl banks, and a 

 comparison of this list with that of Shipley and Hornell (20) will show which genera and species I have 

 not obtained. 



I also append a list of parasitic Crustacea. Trematodes, Nematodes, &c. (mostly new species), 

 ooUectied during the last five years, which await description. 



Owing to my leaving the services of the Company this paper has been prepared hurriedly. 

 Few anatomical details have been dealt with, but it is hoped at some future time to fully describe the 

 anatomical details of all the species dealt with, both in the present and in the preceding Reports. 



In general, the classification adopted in this paper is that followed by Linton. According to this 

 author, the pearl-inducing worm is a Rhynchobothrium. 



The relations of the genera Rhinehothrium and Echeneihothrium require re-investigation, and our 

 species Rhinehothrium Mpleyi, n. sp., appears to require a new genus. 



Larvae of the genus Otdbothrium are exceedingly abunds^nt in the Teleosts found on the pearl 

 l>anks, and it is very remarkable that only a few adult specimens have ever been collected, and these 

 only recently. 



In the present paper ten new species are described, and notes on seven other species are included. 

 A note on a huge species of Trematode from Diagram-ma crassispinum is also added. The following is a 

 list of the species described : — 



Acanthohothrium herdniani, n. sp. 

 Platyhothrium spinulijera, n. sp. 

 Anthobothrium floraformis, n. sp. 

 Anthobothrivni ceylonicum, n. sp. 

 Orygmatohothrium tetraglohum , n. sp. 

 Rhinehothrium shipleyi. n. sp. 

 Spongidbothrium lintoni, n. sp. 

 Syndesmobothrium filicolle. 

 Tetrarhynchus gangeticus. 



Otdbothrium insigne. 

 Otdbothrium linstowi, n. sp. 

 Rhynchobothrium, sp. I. Larvse. 

 Rhynchobothrium , sp. II. Larvae. 

 Rhynchobothrium, sp. III. Larvae. 

 Rhynchobothrium, spp. A, B, and C. Larvae. 

 Rhyncfwbothrium rossii, n. sp'. 

 Paratcenia elongatus. n. sp. 

 Trematode, sp. 



I am indebted to my former Assistant, Mr. George Morrison Henry of the Colombo Museum, for all 

 the drawings which illustrate this paper, and also for the descriptions of two or three species, and I tender 

 my grateful thanks herewith. I would here correct an error made in Part V. of these Reports. The 

 first cestode material from the pearl banks was collected principally bj- Mr. Hornell, and was described by 

 Professor Shipley and Mr. Hornell, and not by Professor Herdman. 



AcANTHOBOTHBiUM, Van Beneden. 



Body articulate, tseniaeform. Head separated from the bodj' by a neck, quadrangular. Bothria 

 four, opposite, attached to head by antero-dorsal side, neck with two transverse costae on face and armed 

 in front with two bifiu"cate hooks, and surmounted in front of hooks by a triangular pad bearing a sujiple- 

 mental disc which is capable of assuming diverse forms. Genital apertures marginal. (Linton U.*) 



Acanthohothrium herdmani, n. sp. (Plate I., Figs. 1, 2, and 3.) 



Measurements. 



Extreme length 



Extreme breadth (at about f of the extreme length of the head) 



Length of head 



Breadth of head 



Length of terminal proglottid 



Breadth of terminal proglottid 



* These numbers refer to the literature cited at the end of tliis paper. 



