NERINE CIRRATULUS. 153 



the aquarium of Wimereux, was rapid, cilia appearing at the third hour. At the seventh 

 hour the prostomium is rounded, with two yellowish-orange eyes and two epaulettes of 

 lateral cilia (from the prototrochal ring). The body is elongated, with a double ring of 

 cilia posteriorly. Three constrictions are evident between the prototroch and the posterior 

 ring, but there is no trace of bristles. The middle part of the digestive tube is greenish. 

 This author (1896) is inclined to think that the Nereis foliata, 5 inches long by four 

 lines broad, of Dalyell, is this species, and he is probably correct. 



Habits. — Mesnil found that they elevate their tentacles very frequently, and turn 

 the furrow backward, and in repose they are placed on the dorsal surface of the body. 



A small form (Plate CI a, fig. 3) procured by the dredge on a sandy bottom at 

 St. Andrews in 1866 appears to approach this species or the previous, though there is 

 considerable uncertainty. The snout is bluntly conical, and is marked by two parallel 

 dark patches just within its border, and another occurs at the base of the snout inferiorly. 

 These are rendered more conspicuous by the presence of pure white specks on the pale 

 portions. The eyes are black and four in number, the anterior pair more widely apart, 

 and situated a short distance behind the dark dorsal specks of the snout. The tentacles 

 are slightly speckled with white. The body is short, tapered from before backward, and 

 is pale posteriorly. The tentacles are grooved and ciliated, and palpocils are also present. 

 Each contains a coil of a blood-vessel. The intestine runs in a straight line from end to 

 end, but is constricted at each dissepiment, and the posterior end is richly ciliated. At 

 the tenth segment its calibre is increased, and it acquires a deep, dull yellow hue from 

 the chloragogenous glands. A large blood-vessel crosses the posterior part of the ninth 

 segment on each side. The branchial processes, the first of which is seen in the figure, 

 contain a coil of a blood-vessel, and each is furnished with two bands of cilia. The 

 posterior bristles are all winged, and hooked at the tip. From the eleventh to the twenty- 

 eighth segment the bases of the feet are crowded with comparatively large ova, measuring 

 from -3t}oth to 3- jo^h °f an inch, each filled with granules and possessing a nucleus. 



The exact relationship of this form is at present undetermined, though it may be 

 related to N. cirrakdus, with which the shape of the snout and the eyes agree, yet no 

 occipital tentacle was seen. The branchia also arises in front — it may be on the second 

 segment. The occurrence of the large ova would appear to indicate maturity in an early 

 form, unless it is a Spin. 



De St. Joseph (1894) found the intestines of examples (his N. longirostris) from 

 Dinard filled with Rissoa parva, whilst on the branchiae Trichodina pediculus occurred, 

 and in the tissues of the body encysted Distomes which might have come from the 

 Rissoa. 1 The same author found an example with brownish ova, having the typical 

 hexagonal reticulation. 



Cunningham and Ramage (1888) describe the ova as pelagic, their external membrane 

 reticulated with hexagonal meshes, and round the longest circumference a single series of 

 vacuoles in the external region of the vitellus, whilst the segmentation is complete and 

 unequal, and a gastrula is produced by epibole. By-and-by the bands of cilia project 

 through this reticulated coating. The authors also represent two later stages of the 



1 See Villot, " Organis. et devel. Tremat. par. Marine/' ' Ann. Sc. nat./ 6 e ser., t. vii, pi. ix, fig. 7. 



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