478 Records of the Indian Museum. [Vol. VIII, 



differs noticeably from that of Eoperipatus^ in which two secon- 

 dary papillae are found on each side behind the primary papilla. 

 The elevations mentioned above do not seem to represent vestigial 

 secondary papillae. 



Ventral organs. 



In the young specimens the ventral organs are distinctly seen 

 in external examination, occurring as small whitish areas, in 

 some of which a minute aperture is visible, in the mid- ventral line 

 between the leg- bases. In the adults I have been unable to dis- 

 cover any trace of them, either on external examination or in 

 sections. 



Genital apertures. 



The genital aperture in both sexes is found between the limbs 

 of the penultimate pair. The orifice is frequently cruciform in 

 shape and is surrounded by the customary tumid, papillose lips. 

 The accessory glands of the male open separately, in this respect 

 differing from those of Eoperipatus. The two orifices are very 

 inconspicuous ; they are provided with srriall whitish lips and are 

 placed side of side behind the base of the last pair of limbs (pi. 

 xxxiv, fig. 7). 



Internal Anatomy. 



The internal anatomy of Peripatus has been so minutely in- 

 vestigated that it is only necessary to discuss a few points in an^^ 

 detail. 



Nervous system. 



Although no trace of the eye is visible externally the optic 

 ganglion is well-developed and has the form of a spherical mass 

 situated laterally at the base of the antennary nerve (pi. xxxv, 

 figs. I, 2, o.g.). The skin overlying the ganglion is wholly un- 

 differentiated and bears papillae precisely comparable to those of 

 the surface in the near vicinity. The epidermis is not specialized 

 to form a cornea, the lens is entirely absent and there is no black 

 retinal pigment. 



The optic ganglion comprises a large number of ganglionic 

 cells, but does not form a solid mass. Sections passing through it 

 show that in the centre there is a cavity which ramifies irregularly 

 throughout the ganglion and is lined by a loosely compacted non- 

 cellular structure. On comparison with the fully developed eye 

 in Peripatoides novae zealandiae (Hutton) , it is evident that the struc- 

 ture which lines the cavity represents the remains of retinal rods, 

 and it appears that the ganglionic cells which originally formed a 

 cup-shaped mass round the base of the retina have grown round 

 the base of the rods and have completely enveloped them. The 

 optic nerve is well- developed and is broadly expanded within the 



1 See Evans' fig. of E. Iiorsti, Quart. Journ. Microsc. Sci., XLIV, pL xxxiv, 

 fig. 17, 1901. 



