366 OPHRYOTROCHA PUERILIS. 



In front of each anterior eye is a small tentacle of two segments, the basal shorter than 

 the distal, which is bluntly rounded and furnished with palpocils similar to those on the 

 anterior arch. A pair of tentacles having the same structure occupy a corresponding 

 position on the ventral surface of the snout, but they are more external in position so that 

 they project distinctly on each side. Claparede and Mecznikow describe a ciliated groove 

 between the head and the following segment. 



Body from 8 or 9 mm. to nearly half an inch in length, with more than thirty bristled 

 segments. It is little tapered anteriorly, and only slightly so posteriorly. It is pale and 

 semi-translucent, the internal organs, viz., the blackish dental apparatus and the straw- 

 coloured or greenish alimentary canal, being visible from the exterior. Two segments 

 behind the head are devoid of feet. The feet project outward somewhat stiffly. 

 Posteriorly are two clavate cirri provided with palpocils which proceed from a caudal 

 segment devoid of feet. 



The armature of the proboscis (Plate LXI, fig. 10 a) consists of dark-brown or blackish, 

 strongly curved, and sharp-pointed maxillae, behind which an acute posterior process 

 projects. Six denticles, which probably represent the dental plates of allied forms, occur 

 beneath and in front of these, each being shaped somewhat like a hoof, the free edge 

 anteriorly being finely denticulated. They diminish in size from before backward, the 

 last having a long slender process which reaches the posterior border of the maxillas. 

 Young examples have a smaller number of denticles. The mandibles are elongated and 

 curved like the letter f, a wing-like border occurring close behind the anterior region. 

 The cutting edge is bifid, and both cusps are minutely crenate. 



"When fully formed the foot (Plate LXXIII, fig. 7), like that of Staurocephalus Kefer- 

 steini, has no dorsal cirrus, but projects somewhat stiffly outward with four conical 

 terminal processes. At the upper end is the conical dorsal lobe, which rises from the 

 dorsal margin of the foot by a long stiff slope, whilst the distal border is shorter and 

 more nearly vertical. Beneath is the blunt or expanded conical process for the long 

 translucent spine, one margin of the foot then trending obliquely outwards into the 

 elongated process for the compound bristles of the region, whilst the other leads to the 

 ventral lobe, which is less prominent than the other processes, that is, is nearer the body, 

 as usual in the group, and has a long ventral and a shorter distal slope. The bristles 

 also differ from those of any other species observed. Dorsally above the spine are about 

 three elongated translucent bristles (Plate LXXXII, fig. 1), with slightly flattened tips 

 (in one short) which end in a short point slightly hooked. No serrations are visible on 

 the edge in the preparations. Below the spine and little separated from the upper series 

 are about six compound bristles equally translucent. The shafts are curved toward the 

 end, which is also dilated and bevelled for the terminal piece. The two upper bristles 

 are as long as the dorsal, but the rest diminish in length interiorly. All, however, are 

 proportionally long. The terminal pieces appear to be simple, but it is sometimes very 

 difficult to observe a minute secondary process if close to the point (Plate LXXXII, fig. 1 a). 



Reproduction. — All the examples observed, and they were under observation for several 

 months, had large ova internally, their longer diameter being nearly equal to the vertical 

 diameter of the foot. Mr. Garstang thought the breeding season of the species was in 

 August, but Dr. Allen has since found it spawning in the tanks in May. 



