ON A NEW ECHIUROID. 



63 



and is fixed to the integument by very numerous thread-like and 

 membraneous muscles, the latter being present especially at the places 

 where it lies close to and nearly parallel with the ventral nerve-cord. The 

 manner of winding and the relative length of different parts of the 

 alimentary canal is, on the whole, as in Hamingia arctica and in 

 many species of Thalassema. The whole canal may conveniently be 

 divided into three parts ; the fore-gut (inch pharynx, oesophagus, crop, 

 etc. of other workers), the mid-gut with the collateral intestine, and 

 the hind-gut with the ciliated groove. These three parts are respectively 

 27.5 cm., 30 cm. and 35 cm. long. Owing to the U-shaped bending of 

 the posterior portion of the fore-gut, the junction of the latter with the 

 mid-gut is brought considerably forwards (see Fig. 4). The description 

 and figures given by Danielsen and Koren of the pharynx of Hamingia 

 arctica may be said to be directly applicable to that of the present 

 species. The pharynx (Fig. 4, pJi) is a large oblong and highly muscular 

 sac measuring 20 mm. in length and 1 1 mm. in maximum diameter, 

 and is firmly fixed to the integument by numerous radial muscles. 



The anal glands, which are found in the usual position, show 

 some peculiarities. From the terminal portion of the rectum arise 

 three main canals on each side, each giving off secondary and tertiary 

 branches before ending with the funnels. Fig. 2 represents the main 

 as well as the principal secondary and tertiary canals (see right-hand 

 side) in natural position. There are on each side two larger, antero- 

 ventral (iw) and postero-dorsal canals (/>d), and one smaller, mid- 

 lateral (////) main canal. The two antero-ventral canals run so ventral 

 that they make very acute angles with the ventral nerve-cord (i>nc). 

 As may be seen on the left-hand side of the above figure, the three 

 canals seem to originate independently from a narrow and thin-walled 

 outgrowth {rd) of the rectum. It seems probable that this saccular 

 outgrowth, one on each side, is homologous with the large vesicles 

 described by myself in Protobonellia mitsukurii} The long-stalked 



I. Ikeda, I., — Note on a New Deep-Sea Echiuroid, Protobonellia mitsukurii : Auiiot. 

 Zool. Jap., Vol. VI, part 4, 1908. 



