263 CEYLON MARINE BIOLOGICAL REPORTS. 



It may be necessary later to refer tliese specimens to a new genus, in which the unpaired cliaracti^r 

 (if {lie areolas on each bothridium and the absence of a myzorhynchus are characteristic. Otherwise 

 Piesing's description of tlie genus Echcnrihothrinm must be modified so as to include forms in which a 

 myzorlij'nchus is absent, or else Lhiton's genus B/iinebothrium must be modified to include forms in 

 whicli the bothridia may or may not be divided by " one or a few muscular partitions." 



On the whole it would ajipear wiser and simpler to establish a new genus for the forms just 

 described. 



Spongiobothrium, Linton (IJ). 



Characters amended (1891). 



Body articulate, tseniseform. Head separated from body by a neck. Bothria four, in lateral 

 pairs, pediceled, with crisp, folded, or auriculate edges, which are crenulate, and the auriculate flaps finely 

 costate on account of a marginal row of loculi with muscular borders ; unarmed, and without transverse 

 costae on face. No myzorhynchus, no supplemental discs. Genital apertures marginal. 



Spongiobothrium lintoni, n. sp. (Plate II., Fig. 14.) 



The head consists of four bothridia, with a row of tiny loculi round the edges. Each bothridium 

 is roughly oval in shape, and is attached by a rather short stalk. Opposite the point of attachment each 

 bothridium appears to be almost divided transversely into two halves, and their edges are indented. 

 Placed centrally and opposite to the point of attachment is a minute fiask-shaj)ed depression on the face 

 of each bothridium, which at first was mistaken for a sucker. Careful examination, however, showed that 

 the two halves of a bothridium are capable of movement, simulating the movements of the parts of a hinge. 

 When the faces of the two parts of the bothridium are apposed the central depression is noticeable, but 

 when they are separated from each other and flattened, tliis structure is hardly visible under a low power. 

 In shape the bothridia resemble those of Rhinehothrium insignia, Southwell (23), but the areolas are very 

 differently distributed. The number of loculi round the margm vary greatly. In some specimens they 

 are very pronounced, whilst in others they are only found with difficulty. There are no transverse or 

 longitudinal septse and no myzorhynchus. The average breadth of the head is 1 mm., and the length 

 •6 mm. The neck is very short, being about '4 mm. long and about -2 mm. broad. The anterior half of 

 the neck is usually clear and transparent. The length of the worm is 20 mm. The average number of 

 ])roglottides is twelve. The first segment is square, or nearly so. They elongate rapidly, however. The 

 sixth segment is twice as long as broad, and the last segment is 4 mm. long and • 5 mm. broad. The sides 

 of the proglottides are slightly convex. The genital apertures are lateral and irregularly alternate. Only 

 the last two segments appear to be mature. The penis is • 6 mm. long, very narrow, with a bulbous base. 



The diagnosis of Spongiobothrium lintoni, n. sp., is as follows : Small worms, 20 mm. long and 

 •5 mm. broad. Head with four leaf-like bothridia borne on short pedicels. Each bothridium has a 

 marginal row of loculi, and is divided transversely at the centre. From this pomt the halves of each 

 bothridium move like the parts of a hinge. When apposed a flask-Mke depression is to be seen, which is 

 difficult to observe when the two halves are not apposed. Myzorhynchus absent. Neck very short. 

 Usually twelve segments present. First segment square. Last segment 4 mm. long, and eight times as 

 long as broad. Genital apertures lateral and irregularly alternate. Usually only the last two segments 

 mature. 



Habitat. — ^The spiral intestine of Rhynchohatus djeddensis (Forsk.) and Vrogymnus asperrimu 

 (Bl. Sclin.). Eight hundred and fifty specimens. February, 1911. 



So far as I am aware, only one species of this genus has been described, viz., Spongiobothrium 

 variable, Linton. Our specimens answer perfectly to Linton's description of the genus, but differ from 

 Spongiobothrium variable, Linton, in the nature of the bothridia and the segmentation, and in the presence 

 of a flask-like depression on the face of the bothridia. 



I have pleasure in naming this species in honour of Dr. Edwin Linton, whose work on American 

 Marine Cestoda is so well known. 



