SPIRORBIS SPIRILLUM. 395 
different angle, representing the main fang. The inferior edge is more or less straight, with 
a small incurvation behind the main fang. 
Reproduction.—Ova in various stages of development occur in the ccelomic cavity of 
females in summer, and nearly ripe sperms in the males at the same time. 
Claparéde and Mecznikow’ (1868) remark that this species, their S. Pagenstechert, is not 
hermaphrodite ; also that, so far as they can learn, the larva is not developed in the operculum, 
and that their form had the young in the body-cavity. They describe two young stages, 
in the first of which the cephalic lobe has a long whip of cilia in front, two eye-specks anteriorly, 
a larger pair behind, a prototroch on a prominent ring, an enlarged segment and several 
smaller behind it. Mouth and anus are present. The next stage has a lobulated cephalic 
lobe with similar eye-specks, and the body shows traces of more numerous segments 
anteriorly. It is, however, doubtful if they refer to the same form as here described. 
The tube (Plate CX XXII, fig. 6d) is dextral, that is, the coil is from left to right, 
is quite smooth, and more or less translucent, the aperture in some being raised, so as to give 
a lax aspect to the spire. It is flattened and less smooth on the attached surface—where 
fixed to the zoophyte. Other tubes, again, have a more elongated spiral, the aperture with 
the last coil being raised, so that it projects considerably above the rest. 
In the plate of Pallas (1788) the animal is figured in its tube with four branchial plumes, 
but no operculum. 
This is the Sprrorbis lucidus of Montagu, who, along with Fleming, sometimes confounded 
another form, viz., Sp. borealis, so common on Fuci, with Sp. sprrillum. He (1803) describes 
it as frequently having the aperture turned upward, with the volutions rising spirally on 
each other and attached by the small end. He notes that it seldom occurs on stones, shells 
or crabs, like S. borealis. He thought that a smaller kind on Corallina officinalis was different. 
Morch separated S. lucidus, Montagu, from S. spirillum, but most authors consider it 
a variety of the latter. He included three varieties under the title, viz., the typical S. lucidus, 
var. 3, cornea, and var. y, grenlandica (S. porrecta). In the British Museum is a specimen 
labelled S. lucidus from Smith’s Sound, Halifax, N.S., 80.9.27.66. The annelid is of a deep 
red colour, and the collar-bristles have no web, as in S. sporillum. The tube is smooth, 
cylindrical, with a rounded aperture, and. the umbilicus is filled by the early coils. The 
operculum is flat. The confusion arising from dependence on the appearance of tubes without 
investigation of the inhabitant has been considerable, and the present is another instance. 
S. spirillum and its varieties are almost cosmopolitan. The variety sinistrorsa, Montagu,’ 
is a larger race than that usually found on zoophytes, and examination of the fresh form 
would set doubts at rest. It was thought to be a distinct form by W. Cocks. It occurs on 
lobsters’ claws and on shells. It is figured by Walker (‘ Minute Shells,’ figs. 13 and 14), and 
appears to be S. armoricanus, De St. Joseph. Montagu (1803) describes it as having a semi- 
pellucid, glossy, white shell, with two or three reversed volutions usually placed laterally, 
sometimes coiled on each other. It is somewhat wrinkled transversely, but has no longi- 
tudinal irregularities. The aperture is orbicular, diameter 1 line. It appears to be a 
reversed S. spirillum occurring on Crustacea. Johnston includes it under S. lucidus. Caullery 
and Mesnil found intermediate forms between S. armoricanus and S. spirillum. 
' ‘Zeitschr. f. wiss. Zool.,’ Bd. xix, p. 199, Taf. xvi, figs. 2 and 2a. 
“Test. Brit.,’ ii, p. 504. 
220 
