20 DR JOHN RENNIE AND MR ALEXANDER REID ON 



Description of Species. 



Ariola (l) divides the family Bothriocephalidae as under : — 



Sub-families : 



Diflogoninae. Two sets of gonads to each segment. 



Mesogoninse. A single set of gonads ; genital apertures on surface, All the 



Bothriocephalidae found, with one exception, belong to this group. 

 Pleurogoninw. Marginal genital apertures. 



One of the species found, Anchistrocephalus microcephalus, Rud., belongs to this 

 group. 



Order PSEUDOPHYLLIDEA, Carus. 



Family Dibothriocephalid.e, Liihe. 



Sub-family mesogonin^ (Ariola). 



Genus Dihothriocephalus (Liihe). 



Dibothi'iocephalus scoticus, n. sp. (PI. I. figs. 1 and 2.) 



This form occurred in the intestine of a Sea-leopard {Stenorhynchus leptonyx). 



The maximum dimensions are : strobila, length 13 ".3 cm., breadth 6*8 mm. ; scolex, 

 2"5 mm. by Vb mm. The scolex when fully extended shows a pair of dorso- ventral 

 suckers widely gaping posteriorly and tapering towards the tip, which is rather sharply 

 conical. The sucker lips are rather thin, almost weak. 



No distinct neck is present. The proglottides are fairly broad, with well-marked 

 backwardly directed flanged margins. Anteriorly they are roughly rectangular, much 

 shorter than broad ; in the mature parts of the strobila they become relatively longer. 



The cuticle is rather thin, and beneath it an extremely fine circular layer of muscle 

 can be made out with ditSculty. Next this is a longitudinal layer, also slightly 

 developed. This longitudinal layer lies between the narrowed ends of the cellular sub- 

 cuticula, whose elements form a clearly defined band. Following on this is the layer of 

 the yolk follicles, which, in the mature segments, except at the level of the uterus and 

 cirrus sac, forms a practically continuous band. Within this occur two muscle layers, 

 a well-defined longitudinal layer outerniost ; while, within, a thin circular band separates 

 the peripheral area from the central. 



The longitudinal nerve cords are placed about one-fourth of the transverse diameter 

 from the margin. 



In the mature segments there are about nine testes follicles external and about six 

 internal to the nerve cord on each side. 



Central longitudinal excretory canals were not observed, but there are numerous 

 small peripheral canals in the subcuticula just external to the yolk follicles. 



The yolk cells are extremely variable in form and size, and may be described as 



(ROY. SOC. EDIN. TRANS., VOL. XLVIIL, 442.) 



