HETEROCIRRUS VIRIDIS. 261 



before backward is corroborative of that view. In some the tips are spatula-shaped, 

 a slight constriction occurring at the neck. One or two capillary bristles, with a slight 

 flattening of the serrated tapering tip, accompany the dorsal hooks. 



Reproduction. — Several procured at Guernsey and Herm in July and August had 

 well-developed eggs. Moreover, an epitokous example (male, more than 2 inches 

 long) occurred amongst the others at St. Peter Port, Guernsey. In this the anterior 

 region of about thirty segments is modified, whilst the caudal of about thirty segments 

 does not present a noteworthy change. The pigmented area of the eyes is perhaps a 

 little larger, and the dorsal tuberosity of the head somewhat more prominent, whilst the 

 tentacles and branchiae are normal. The whole of the anterior and middle regions are 

 enlarged, softer, and have long resplendent dorsal swimming bristles, which exceed in 

 length the diameter of the body. They are smooth simple tapering bristles, with very 

 faint longitudinal lines, and of a pale yellow hue, best seen by transmitted light, and 

 their tips are remarkably attenuate. The anterior dorsal bristles are not much changed, 

 but from the eighth to the thirty-first they form conspicuous tufts on each side. This 

 bristled region with the head is probably thrown off and emits the sexual elements, 

 whilst the unchanged and flattened posterior moiety of about thirty segments reproduces 

 a head and anterior region. The fact that this example, which was not quite ripe, still 

 occupied its tube in Lithothamnion, would indicate that up to the period of " swarming " 

 the oar-shaped posterior region and its series of powerful hooks would be of material 

 service to the form, and, further, after the separation of the sexual region, if such is 

 found to occur, the remnant would be ready for the exigencies of its life in the calcareous 

 crusts and masses. The great size of the hooks or crotchets throughout, and especially 

 in the posterior region, shows that the form is adult, and that the shovel-shaped and 

 abraded posterior hooks have been in constant use. In the dorsal division (with two 

 hooks) are one or two of the tapering capillary bristles, the anterior edge of the tip of 

 each of which is serrated. 



The Heterocirrus saxatilis of Grube 1 (1855) may be the same or an allied form, and 

 the same may be said of his Heterocirrus multibranchis* (1863). 



De St. Joseph (1894) describes three new species from Dinard on the French coast, 

 each apparently differing from the other in the distribution of the bristles and in coloration. 

 It is possible that further study may simplify the series. 



Heterocirrus fimbriatus, Verrill, is the pelagic form of Dodecaceria concharum. 

 According to Caullery and Mesnil, Langerhans again shows a young form of B. (small 

 pelagic). The species is polymorphic in its sexual phases. 



2. Heteeocieeus vieidis, Langerhans, 1880. Plate CXI, fig. 9— head, and figs. 9 a, 9 b— 



■ bristle and hooks. 



Specific characters. — Head forming a more or less acute, but flattened cone with two 

 large eyes placed over the posterior region of the cerebral ganglia. Nuchal organ on each 

 side a little behind the eye. Two achsetous segments follow, the second, that behind the 



1 f Arch. f. Naturges./ Bd. xxi, p. 109, Taf. iv, fig. 11. 



2 Ibid., Bd. xxix, p. 49, Taf. v, fig. 2. 



