416 SPIRORBIS MILITARIS. 
division. The thoracic excretory organs correspond with those of other Serpulids, viz., a 
lateral funnel on each side, then an angular bend into the canal, which meets its neighbour 
of the opposite side, and terminates in the single duct opening dorsally. The pale greenish 
blood is sent from a ring behind the ganglia to the branchie, the anterior end of the sinus 
behind it functioning as a contractile heart, which sends blood not only to the ring, but 
into the ventral trunk. In the abdominal region he shows ring-vessels in each segment to the 
tip of the tail. The nervous system has two chief cephalic ganglia, the two main trunks with 
enlargements in front, and connectives behind, also with ganglionic enlargements. A main 
feature of the paper is the consideration of the asymmetry of the body and most of its organs, 
even the bristles and hooks of the two sides sharing in the irregularity. He endeavours to 
explain the action of the asymmetrical muscles by ingenious diagrams in text and plate. 
Fauvel (1914) holds that his form is not that of Montagu, Fleming or Pagenstecher. 
The facts that the tube is sinistral, that the first bristles have no gap at the base of the tip, 
and that the eggs are developed in the tube, would appear, amongst other things, to show 
that 1t 1s the common form. 
Southern (1914) considers there are two forms of this species, viz., those with smooth 
tubes on seaweeds, etc., and those with ridged tubes on rocks. He holds it is the S. borealis 
of De St. Joseph. 
B. Incubation in Operculum. 
8. SPIRORBIS MILITARIS, Claparede, 1868. Plate CXXII, fig. 12—operculum; Plate 
XXXIT, figs. 7 and 7b—bristles; Plate CX XXVIII, fig. 16—anterior hook. 
Specific Characters—Cephalic collar typical. Branchie reddish, have comparatively 
thick filaments, and the terminal process is long and tapered. Operculum helmet-shaped, 
with denticulated ridges and accessory spines. The ova are developed in its cavity. Body 
typical in outline, and of a deep or pale reddish hue. ‘The first bristles are characterised 
by their large size, yellow colour, and the coarseness of the serrations on the terminal blade, 
which has a distinct gap above the web at the base. The anterior hooks have about twenty 
sharp serrations along the anterior edge, and their outline is more acutely triangular than 
usual, with boldly marked striz sloping downward and backward, each tooth parallel to the 
posterior border and to each other. The terminal process or main fang is comparatively 
small, with a slight bay behind it. Tube smooth, comparatively large, with a rounded 
aperture, which projects from the surface of the Lithothamnion, in which the rest is immersed. 
Claparéde (1868) constituted the genus Pileolaria for this species, the characters of which 
were the presence of an ordinary thoracic membrane, few branchiz, a calcareous, compressed 
operculum with denticulations, and a coiled calcareous tube. It does not appear to be 
necessary to resort to a new genus, and such was the opinion of Caullery and Mesnil. 
SYNONYMS. 
1833. Serpula spirorbis, Scacchi. Catal. conchyl. reg. Neap., p. 19 (fide auct.). 
1868. Pileoluria militaris, Claparéde. Annél. Nap., p. 444, pl. xvi, fig. 5. 
5s s A Claparéde and Mecaznikow. Zeitschr. f. wiss. Zool., Bd. xix, p. 200, Taf, xvi, 
fig. 3. 
