30 Pi of. M'lntosh's Notes from the 



Avitlun [i. e. dorsad to) the first bristle-tuft^ and is smaller, 

 whilst the third^ which is somewhat larger, arises on the 

 dorsum opposite the second bristle-tuft. Th,e first pair is 

 widest apart, the third pair most nearly approach each other. 



The body generally resembles that of the foregoing form, 

 but is often smaller, and the dorsal and ventral surfaces, 

 glandular scutes, and plates do not materially differ. The 

 bristle-tufts range from thirty-three to forty, the posterior 

 region, in one of forty segments, being devoid of them, as 

 in T. cincinnatus. It tapers posteriorly to a slender tail, 

 and the uucinigerous processes seem to go on to the tip, 

 thus differing from those of T. cincinnatus. The anus 

 appears to have a papillose margin. 



The first bristle-tuft arises opposite the second branchia, 

 and, as mentioned, is above the level of the first branchia, 

 and the setigerous processes are continued along the dorso- 

 lateral region to the posterior region, as in Thdepus cincin- 

 natus, where they cease. The setigerous processes are 

 vertically flattened in front and throughout the greater part 

 of their course, but posteriorly they diminish to conical 

 papillae. The anterior bristles appear to be somewhat shorter 

 than ia T. cincinnatus, but are similarly arranged in two 

 series, a longer and a shorter. The wings in both are 

 slightly broader than in T. cincinnatus, both sets of bristles 

 being proportionally shorter and thicker. They increase in 

 Icngtli in the middle of the body, but posteriorly diminish 

 both in size and number, especially before ceasing, yet re- 

 taining the same arrangement as regards shorter aud longer 

 series. The wings in the terminal bristles are narrow. 

 All the bristles have a pale golden hue, and, whilst the first 

 few sets of bristles are directed outward, the majority slope 

 outward and backward — the terminal tufts, however, in the 

 preparations, projecting outward or even slightly forward. 



The rows of hooks commence on a fillet on the fifth 

 segment (that is, opposite the third bristle-tuft, at the pos- 

 terior part of the segment), and they slightly increase in 

 length to the fifteenth series, when a gradual diminution 

 occurs, the rows, moreover, by-and-by being elevated on 

 processes, and, iiistead of being nearly straight, they are 

 convex forward about the twenty-fourth, and this arrange- 

 ment appears to be retained in the longer posterior uucini- 

 gerous processes, where they occur on the anterior face of 

 the tip. As the bristles diminish and disappear, the uucini- 

 gerous processes increase in prominence, and are ventro- 

 lateral in position. Finally, they are minute toward the 

 tip of the tail. The hook is similar (generally) to that of 



