THE ANATOMY AND DEVELOPMENT OF PERIPATUS NOVAE-BRITANNIAE. 



9 



plane with the bladder ; (4) an inner vesicle whose walls usually appear shrunken in 

 section — this is Sedgwick's end-sac, and is a remnant of the true coelom into which 

 the funnel opens. In a series of sections through a young female (IX) of P. novae- 

 britanniae, Sedgwick's end-sac can be demonstrated with the utmost clearness (see 

 Text-figure 1). It can also be easily seen in sections through a mature female (III). 

 The thin membranous wall of the vesicle passes with characteristic abruptness into 

 the thick glandular wall of the funnel. As I shall have further occasion to point out, 

 there is a similarly sudden transition in the connection between the thin-walled ovarian 

 tubes and the thick-walled oviducts, though this is not so pronounced when seen in 

 section. Both Kennel and Gaffron missed the nephridial end-sac which was discovered 

 by Sedgwick. 



,c tn 



Fig. 1. Semi-diagrammatic transverse section throdgh a young female of P. novae-britanniae. 

 The segmental organs are represented as seen in a single slightly oblique section. The structures in 

 connection with the nerve-cords are inserted from a combination of several consecutive sections. The ventral 

 nerve-cords are connected with each other by a commissure and with the ventral organ by cellular cords. 

 b. bladder of segmental organ, cm. circular muscles, d.m. diagonal muscles, e.s. Sedgwick's end-sac. /. funnel. 

 f.b. pericardial cell-groups (so-called fat-bodies), h. heart, l.m. longitudinal muscles, n.p. nephridiopore (a 

 portion of the cuticle is shown entering the ectodermal portion of the excretory tubule), r. rectum, s.m. 

 sagittal muscles. 9jO. segmental organ, t.m. transverse muscles, tt. uteri, v.o. ventral organ. 



There are no segmental organs corresponding to the last pair of legs, either in 

 male or female, in this species; and in the male I have not found a dilated bladder 

 in the nephridia of the 20th and 21st leg-bearing segments. In my sections through 

 these segments the proximal excurrent portion of the nephridium is simply tubular. 



Female Reproductive Organs. 



On opening a mature female, the first structures to meet the eye are the coils 

 of the uteri and the ramifications of the slime-glands (Fig. 12). The latter extend 

 backwards as far as the ovary, and their smaller branches cohere and intermingle with 

 the convolutions of the uterus. It may be that the slime-glands of Peripatus are com- 

 parable to, if not homodynamous with, the cement-glands of Cirripedes, which also 

 interdigitate with the genital organs. 



