230 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Ser. 



Genital Zone. — (fig. 83.) This zone is small but distinct. 

 It commences with somite XVI and ends with somite XVIII. 

 It is very narrow, of about the width of a somite, except in 

 the centre, where it is about twice as wide. The whole 

 zone is sunk as in Benhamia and surrounded by an elevated 

 ridge of clitellar cells. There are no distinct markings of 

 the somites in the zone, except at the boundaries. There 

 are two male papillae in the centre of the zone, from each 

 one of which protrudes the large, almost straight apex of a 

 penial seta. 



Lymphocytes and Cells of the Body-wall. — (figs. 91, 113.) 

 The prostomium is well developed and its epithelial cells 

 are taller than the cells of the nearest somites, tapering 

 towards the interior and ending in a fine hair-point. Such 

 cells are also, though more sparingly, found in the epidermis 

 of the other somites, interspersed among ordinary support- 

 ing cells. They stain differently from the latter, being more 

 erythophile, while the supporting cells are decidedly cyano- 

 phile. In the former pages of this paper it has been pointed 

 out that similar cells are found in large numbers in the cau- 

 dal zone of Pontoscolex, and it is stated as my opinion that 

 they are probably sense-cells, especially responding to 

 vibrations transmitted through the soil. 



On the inner side of the prostomium, but especially on the 

 two inner lips or ridges separating the mouth from the palate, 

 we find groups of regular taste-cells, each with a fine hair- 

 point. They occur in bunches of twenty or more, and the 

 hair-points frequently project through the cuticle in such 

 numbers as to give the cells the appearance of being ciliated. 

 These cells stain much deeper than the other sense-cells. 

 They have the same general form. 



Dr. R. Hesse in a most admirable paper (2) has described 

 a number of cells of very distinct construction, which he 

 supposes, and as it appears with very good reason, to be 

 cells sensitive to light. Cells of a similar nature are found 

 in considerable numbers in the prostomium of Dichogaster 

 Crawi. Their structure is similar to that of the light-cells 

 of Alloloho-phora arbo7'ea, as figured by Hesse. They vary 



