324 
ZOOLOGY OF THE FAR EAST. 
Fisheries, Bengal, Bihar and Orissa, for kindly allowing me to continue my zoological 
studies in my spare time and for permission to publish this paper. 
In this paper I have devoted special attention to the structure of the proboscis, 
the segmental organs and the anal vesicles, structures which seemed to have a special 
interest in this group of species and required investigation. 
ORIENTAL ECHIUROIDEA OF BRACKISH WATER. 
External Characters : — I have nothing to add to the admirable account of the 
external characters of T. dendrorhynchns and T. branchiorhynchus by Annandale and 
Kemp (2), but a few remarks about the natural colouration, other external characters 
and the locality of T. sabinum are given as a supplement to Lanchester's description 
(7)- 
Dr. Annandale' s single specimen was collected in the inner end of the outer 
channel of the Tale Sap on the 30th of January, 1916. The specific gravity of the 
water corrected to 15 °C. was 1-004. "^^^ animal was found living in soft mud 
containing dead shells. 
In the living specimen the integument was colourless and hyahne, with minute, 
round and colourless papillae. Anal vesicles tinged with yellow ; intestine full of 
mud ; hooks very slender, silvery, in preserved specimen rather yellowish ; nerve 
cord opaque, seen through the integument ; proboscis less hyaline than the body, 
capable of considerable change of shape but not very extensile, ventral margin not 
fused. The animal wriggled slowly and contracted itself at various points, and 
formed a sheath of mud round itself. 
In the preserved specimen the skin has a creamy colour. The papillae as shown 
in text fig. I, are very minute, and collected together on the anterior third of the 
body. Over the rest of the surface there are nearly 
regular rows of large papillae alternating with much 
smaller ones. The preserved specimen measured 11 mm. 
in length. 
Setae : — The setae of T. sabinum are of the normal type. 
In T. dendrorhynchns and T. branchiorhynchus in accord- 
/ " \ ance with their habitat (which is discussed at length in 
|: the account of the proboscis) they are modified ; in the 
latter form more so than in the former. 
In r. branchiorhynchus the setae (fig. i) are rather long 
V ^ and specially curved at the anterior end ; this curved 
portion is always outside the body while the straight por- 
FiG. i.—Thalasscma sabinum. tion projects into the body-cavity, and the large radiating 
i^anchester, as seen from the musclcs on the vcutral surfacc of the body-wall anteriorly 
upper surface. , , . , ^ , ^ . 
are attached to its base. The curved outer portion seen 
in a side view is pointed ; viewed from above it has the distal end specially 
thickened along the outer edge and sharpened along the inner. This inner edge 
