320 Transactions. — Zoology. 



walled, the walls being columnar : its lumen is bobbin-shaped 

 (PL XXIX., fig. 8). A short pyloric tube communicates with 

 the globular intestine (fig. 1. See also fig. 8, PI. XXIX.). A 

 very short tube leads from the intestine to the dilated end of 

 the rectum, which commences abruptly. For about half its 

 length the rectum is opaque, owing to its glandular character ; 

 in the remainder it is traceable only by the numerous faecal' 

 pellets contained. It does not appear to cross the oesophagus 

 (fig. 1), but much variation is apparent in this particular. 

 The atrial pore is in all cases distinct, and provided with a 

 long languet (fig. 1, a.l.), which shuts against a projection of 

 considerable size below. 



The reproductive organs are striking in character. The 

 male organs consist of a number (usually seven) of spermatic 

 vesicles, situated near the intestine at its rectal end in such a 

 way that their larger free ends turn towards the stomach. 

 Each vesicle is pyriform in shape, and communicates by its 

 small end with the vas deferens, which is very difficult to dis- 

 tinguish near the vesicles, but becomes exceedingly clear in 

 its after-course. Careful focussing, however, shows on each 

 side of the mass of sperm-bodies three small dark objects, ap- 

 parently nucleated, and quite round. If observed carefully the 

 vas deferens may be seen as a transparent thread, equal in 

 w^idth to the diameter of the dark bodies, and uniting them in 

 pairs. This is the usual state, but occasionally the whole 

 course of the vas deferens is traceable around the sj^ermatic 

 vesicles. It then appears to rise from the common apex of 

 the vesicles, encircling them as a narrow transparent tube 

 some three times, after which it dilates greatly and passes up 

 alongside the rectum. In this part of its course it acquires a 

 deep reddish-yellow tinge with picro-carmine (fig. 7). 



Near the rectum and opposite the end of the oesophagus 

 there lies, in a special mantle- swelling, a dark body with clear 

 lumen, which on close scrutiny is seen to be surrounded by a 

 ring of transparent oval bodies, difiering somewhat in shape 

 owing to XDressure, and of various sizes. The dark body is 

 composed of columnar cells, whose outlines are clearly visible 

 (fig. 5, ovr., and fig. 1). This I take to be the ovary with its 

 ova. But if this be correct the ova are certainly not nucleated : 

 at least, not in their present stage. No embryos were found 

 in the colony. 



A last feature, and a puzzling one, remains to be noted. 

 This is the presence, springing from the mantle in the oeso- 

 phageal region, of a large bulb, often nearly half as large as 

 the thorax. It always arises from the side of the zooid (see 

 fig. 2), and usually from its left side. No traces of structure 

 were observed in any cases ; it is opaque and densely granular, 

 appearing, ni fact, almost homogeneous. There is usually a 



