SPIRORBIS MILITARIS. 417 
1875. Pileolaria nilitaris, Panceri. Atti Soc. Ital., vol. xviii, p. 535. 
1880. ? Spirorbis granulatus, Langerhans. Zeitschr. f. wiss. Zool., Bd. xxxiv, p. 123, pl. v, fig. 41. 
1883. Pileolaria militaris, Salensky. Arch. de. Biol., t. iv. 
1885. rs 5 Carus. Fauna Medit., 1, p. 280. 
1893. oi e Lo Bianco. Atti R. Accad. Sc. Nap., vol. v, no. 11, p. 92. 
1897. Spirorbis . Caullery and Mesnil. Bullet. Sc. France et Belg., t, xxx, p. 215, pl. x, 
fig. 25. 
1909. 96 e Fauvel. Bull. Inst. Oceanogr., No. 142, p. 55. 
“ % y var. Sterzinger. Sitzungsber. k. Akad. wiss. Wien, Bd. exvin, p. 1451, 
text-fies. 15 and 16, Taf. 11, fig. 26. 
» Pileolaria *5 Lo Bianco. Mitt. Zool. Stat. Neap., Bd. xix, p. 585. 
Habitat —On the surfaces of stones and rocks encrusted with Lithothamnion between 
tide-marks at St. Peter Port and other parts of Guernsey, and under similar conditions at 
Herm. Abroad it has been found at Naples (Claparéde) ; shores of France (Caullery and 
Mesnil). The tubes are encrusted, as in the Channel Islands, with calcareous algze. Madeira - 
(Langerhans) ; Monaco (Fauvel) ; Suez (Sterzinger). 
This species, which was probably included by Scacchi as Serpula spirorbis, in his 
‘Catalogue of the Shells of Naples,’ has been well known since Claparéde described it as 
Pileolaria militaris in his volume on the Annelids of Naples. It is a southern type, and, so 
far as known, has hitherto been confined in the British area to the Channel Islands, though 
Caullery and Mesnil found it not infrequent on the shores of France, and Langerhans 
mentions a form (his Sprrorbis granulatus, L.), which these authors consider to be only a 
variety from Madeira. It is rarely met with in the Channel Islands. 
The operculum (Plate CX-XII, fig. 12) is comparatively large, helmet-shaped, and orna- 
mented with denticulated ridges and accessory processes. The cavity of the helmet performs 
the function of a brood-pouch, and in those captured in July and August was filled with 
large eggs and embryos, the breeding season at Naples being somewhat earlier, viz., in June 
and July. It differs from such as Sprrorbis Pagenstechert, De Quatrefages, in so far as the 
opercular helmet is ready to receive the ova without further addition or alteration. Its 
specific name has reference to the helmet-like condition of the operculum. 
The branchie have comparatively thick filaments, which end in a long and slender 
process. 
The body is typical in outline, has a deep reddish hue, and the same colour tinges the 
branchiee, the collar and the alar membrane (Caullery and Mesnil). Anterior region of three 
bristled segments. 
The first or collar-bristles (Plate CX XXII, fie. 7) are characterised by their size, the 
coarseness of their serrations, the presence of a distinct gap, and their yellow colour. Moreover 
they are boldly curved at the tip so as almost. to resemble geniculate bristles. They are 
accompanied by a series of simple bristles, which are widest, though they do not quite 
reach the size of the former bristles, at the base and gradually diminish to a delicate 
hair-like tip. The next bristle-tuft has capillary bristles, with finely serrated wings (Plate 
CXXXII, fig. 7a), the shaft in each being nearly cylindrical or very slightly tapered; whilst 
the third has sickle-shaped forms (Plate CX XXII, fig. 75). 
The anterior hooks (Plate CX XXVIII, fig. 16) are acutely triangular, with a bold series 
