THE MARINE TURBELLARIA. 



297 



B. Forms with a single penis. 



10. Pseudoceros gamblei sp. n. (PI. XV. fig. 18). 



Several specimens from Minikoi, Laccadive Group, ' milk-white ' or ' transparent flesh colour ' 

 with purple or dark-blue rims. 



Total length about 12 mm., breadth 6 mm. Mouth opening about 2 mm. behind the 

 anterior margin. Female aperture about 1 mm. behind mouth. Sucker about 1 mm. behind 

 the female aperture. 



A small circular cluster of eye-spots lies over the brain about 1"2 mm. behind the anterior 

 margin. There is a row of eyes along the margin of the 

 tentacles both on the dorsal and ventral sides, which is con- 

 tinuous across the middle line (Fig. 69). 



Sections were cut transversely through the anterior region 

 of the body of a semi-adult specimen. Rhabdites appear to be 

 absent in the epithelium, and the muscle layers of the body- 

 wall are feebly developed. The testes lie, as is usually the 

 case, on the ventral side of the gut, and the ovaries which are 

 immature can be recognised on the dorsal side. The penis is 

 that of a typical Pseudoceroid. The vasa deferentia before 

 uniting to form the muscular ductus ejaculatorius are each 

 dilated to form a vesicula, which is crowded with spermatozoa 

 (PI. XV. fig. 18). 



A feature of the species is the curious shape of the 

 pharynx, which has its hindmost folds produced backwards to 

 form wing-like projections on either side, extending as far back 

 as the level of the female aperture (Fig. 69). 



ire 



B 



Fig. 69. Anterior end of Pseudoceros 

 gamblei. A. from ventral ; B. from 

 the dorsal side. 



p7i. = pharynx, bT.e. = ' brain-eyes,' 

 s. = sueker, J = penis, ? = female 

 aperture. 



11. Pseudoceros tigrinus sp. n. (PI. XIV. fig. 3). 



One specimen from Minikoi, Laccadive Group. 



Total length about 17 mm., breadth 11 mm. Mouth aperture about 4 mm. from anterior 

 margin. Male aperture about 5 mm. from anterior margin. Sucker about 3 mm. from male 

 aperture. 



Ground colour orange-pink, margin and tentacles black. 



On the dorsal side, on either side of the middle line a black band runs from the anterior 

 margin to within a short distance of the posterior margin. These two bands meet each other 

 across the middle line at their anterior and posterior extremities. In addition to these black, 

 triangular patches project inwards at intervals along the margin ; these like the two median 

 bands have on them a few rather large, circular, pink spots, and between these the black is 

 thickly flecked with very small white spots. 



The position of the eye-spots is completely concealed by the pigmentation of the body, 

 which readily serves to distinguish the species. 



The remaining specimens referable to this genus, some eighteen in number, are all very 

 similar to one another in appearance, being of black colour with yellow margins. Two distinct 



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