ON A NEW SPECIES OF SCLEROCHEILUS. 413 



The armature of the second notopodium and neuropodium is composed of 

 two series of capillary chsetee, of about ten and forty respectively, similar to but 

 rather longer than those in the first neuropodium. The chaetse of the anterior 

 row are proportionately longer, and hence there is less difference in length between 

 them and the chaetae of the posterior row. In several of the specimens examined 

 there are in the second notopodium or neuropodium, or in both, two, three, or four 

 furcate chaetae, but these are neither so large nor so well formed in regard to their 

 prongs as those found in the following segments. They are very fragile, and 

 perhaps this explains why they are not seen in preparations of the second parapodium 

 in all cases. 



In the notopodium and neuropodium of the third and following segments the 

 capillary chsetse are similar to those of the second parapodium, but in addition there 

 is an anterior series of furcate chaetae the prongs * of which agree almost exactly 

 in size and proportions with those shown in text-fig. 2 (p. 408), but the shafts are 

 rather shorter. 



The parapodia of S. minutus are very similar to those of the Scotia Bay 

 specimen ; the figure of one of the latter (fig. 6) would serve equally well for a 

 parapodium from about the 36th segment of S. minutus, except that the latter is 

 smaller (about three-fourths the size shown). 



Saint-Joseph states that behind the 22nd segment the parapodia bear neuro- 

 podial cirri, and a similar statement is made by Professor M'Intosh and by 

 M. and Mme. Dehorne. I have examined fifteen well-preserved specimens from 

 different localities — the Adriatic, Saint- Vaast, Plymouth, and the west coast of 

 Ireland — -and find that the most anterior neuropodial cirrus is situated on the 25th, 

 27th, 29th, or 31st chaetiferous segment in the various specimens. Of five specimens 

 from the Adriatic (collected by Grube) in which the neurocirri are preserved, three 

 bear minute cirri on the 25th segment ; in the other two the first neurocirri are on 

 the 27th segment. Of the four specimens from Saint-Vaast, two have the first 

 neurocirrus on the 27th segment, the other two on the 31st segment. The specimen 

 from Plymouth presents its first neurocirrus on the 27th segment. Of the five 

 specimens from the west coast of Ireland, two have the first neurocirrus on the 29th 

 segment, and three on the 31st. In Grube's figure t of S. minutus the first neuro- 

 cirrus is shown on the 30th chaetiferous segment. As Grube J remarked, the cirri are 

 not respiratory structures, for blood does not enter them. They are purely sensory, 

 as the presence upon them of sense-hairs indicates, and are composed of epidermal 

 cells surrounding a thin axial strand, formed apparently of nerve fibrils. 



One of the neuropodia examined, from a specimen from Blacksod Bay, Co. Mayo, 



* In a neuropodium from one of the specimens from Blacksod Bay, Co. Mayo, Ireland, there occurs a furcate 

 ch?eta with an additional (third) prong, arising from between the bases of the two normal ones. This prong is shorter 

 than either of the normal ones, the lengths being— normal prongs, 45/* and 27/t respectively ; additional prong, 18^. 



t Arch. f. Naturg., Jahrg. xxix, Bd. i (1863), Taf. v, fig. 3. 



X 46 Jahresber. Schles. Ges. (1868), 1869, p. 67. 

 TRANS. ROY. SOC. EDIN., VOL. L, PART II (NO. 14). 58 



