SPIRORBIS. 387 
D. The form with angular fin gives rise to a simple blade, broadly angular at the base. 
Sp. armoricanus, De St. Joseph. 
E. Instead of being angular, the blade becomes broadly rounded at the base. Ex. 
Sp. levis, De Quatref. 
F. The blades become long, narrow, regularly tapered and similar in all three fascicles. 
Kx. Sp. Perriert, Caullery and Mesnil. 
She did not notice that the basal “ fin” was double. 
_ Miss Irene Sterzinger’ (1909) gives at the end of her paper on the Spirorbids from Suez 
Caullery and Mesnil’s key to the species and a figure indicating right and left spiral arrange- 
ments in the genus—taking the commencement of the spire from the mouth—the reverse of 
the growth of the tube. 
In dealing with this genus Miss Pixell? (1912) pointed out that the collar bristles are 
distinctive, either having simple blades or possessing a fin-like expansion at the base of the 
blade (tip); but as there are intermediate forms between the two, she suppresses for 
sinistral forms Caullery and Mesnil’s sub-genus Romanchella with the simple blades and places 
all sinistral forms with three setigerous segments in the French authors’ sub-genus Lwospira. 
The second thoracic segment has only bristles with the ordinary tips; whilst the third in 
addition has some with sickle-shaped tips. In the abdominal region the segments range 
from eight to forty, and the bristles are generally geniculate. The anterior and posterior 
hooks are similar, the front edge having numerous fine teeth, with one larger than the 
others. She adopted in the main the classification of the Spirorbids of Caullery and Mesnil 
in her contribution to the Serpulids of the Pacific Coast of North America, basing, however, 
her main groups on the dextral or sinistral condition of the tube, her sub-genera of the 
dextral forms being Paradexiospira (three and a half thoracic segments), Dexospira (three 
thoracic segments) ; whilst under the sinistral fell Protoleospira (four thoracic segments), 
Paraleospira (three and a half thoracic segments), and Leospira (three thoracic segments). 
Her further groups rested on incubation in tube or operculum, on the structure of the 
operculum, and that of the collar and other bristles. 
In a paper on the Polychetes of Vancouver Island and the Pacific Coast Miss Pixell? 
(1912) makes some useful remarks on the classification of the Serpulids, and especially of the 
genus Spirorbis, of which she appends a table giving the characters of the species. 
In a recent account of the Spirorbids of Sweden, Folke Borg* (1917) classifies the five 
representatives according to the number of the thoracic bristled segments, the opercular 
or non-opercular development, the dextral or sinistral arrangement of the tube and the 
structure of the bristles. 
Much has yet to be accomplished in the synonymy of the species, especially as varieties 
of the common forms have been described as distinct species, and it is not always easy to 
consult the original specimens even if these have been preserved. It is unsafe, for instance, 
1 “Deckel u. Brutpflege bei Spirorbis,” ‘Zeitschr. f. wiss. Zool.,’ Ixxxviii, p. 602, 1907, 13 figs. 
and pl. xxxi. 
2)“Proc. Zool. Soc., 1912, part iv, p. 792. 
3 Op. cit., p. 784. 
4 «Zool. Bidrag. Uppsala,’ Bd. vy, 1917, pp. 15—38, 16 text-figs. 
219 
