STHENELAIS BOA. 413 



internal and anterior to the cirrus. The dorsal hairs are prone to deposits of mud, algoid 

 growths, and stalked Infusoria, their colour thus being often brownish or greyish ; while 

 Loxosomse abound on the feet, under the scales, and other parts. 



Pruvot and Racovitza give a good figure, 1 showing the arrangement of the lobes, 

 papillas, and bristles in a typical foot. Dorsally the papilise (stylodes) occupy the 

 anterior region and pass beneath the division. Yentral]y, the flaps, which they call 

 parapodial bracts, envelop the foot above and beneath, as well as superiorly in front, the 

 anteroinferior being scolloped, each process being terminated by a sensitive palpocil. 



Reproduction. — Large specimens in the Channel Islands were laden in August with 

 fairly advanced greenish eggs in enormous numbers. The males had also the peri- 

 visceral chamber charged with sperms, which issued, after immersion in spirit, from the 

 bases of the feet. 



Development. — Larval forms occurred, towards the end of October, with bluish 

 anterior digestive organs in the metatroch stage, with two kinds of bristles, — viz. 

 long, curved, serrated bristles, somewhat like those of Polynoe, and shorter com- 

 pound forms. Viewed from the front superiorly (Plate XXVIa, fig. 22), two eyes lie on 

 each side. An oblique lateral view shows the feet of one side and the caudal cirri. 

 The first and last bristle-tufts are simple and short, and about seven pairs of feet are 

 visible. Only a single, long, and comparatively strong, swimming bristle occurs in each 

 foot, the curved tip being distinctly and somewhat widely serrated on the convex edge. 

 Such, therefore, would appear to be a modification of the serrate dorsal bristle, which is 

 functional at this stage. The ventral bristles had dilated ends to the shafts — with the 

 usual oblique termination and a distal region of two segments. It is uncertain whether 

 these young forms pertained to this genus or to Sigalion. 



Habits. — They are somewhat sluggish animals, usually lurking under stones between 

 tide-marks, where they rest on a sandy bottom, though occasionally small examples are 

 found in pure sand as at Southport. They form curious coils in vessels in confinement, 

 and appear to be nocturnal. So far as my specimens go, the finest are those between 

 tide-marks, Herm, while next to these, and only a very little less, are those between 

 tide-marks at St. Andrews. Those procured in the sand of the Zetlandic voes are much 

 smaller, and the same may be said of those from the outer Hebrides. Average examples 

 come from the west coast of Ireland. 



This species was introduced, in 1833, to science by Dr. Gr. Johnston, who found it in 

 Berwick Bay under stones near low-water mark. He says it is somewhat sluggish, but 

 burrows in sand with rapidity. Moreover that it is the Goliath of its race, and preys on 

 its fellow-worms. It is probable that Rathke, in 1843, referred to this species under 

 the title mentioned (S. Idunae). The Sthenelais Edwardsii of De Quatrefages (1865) 

 seems to be this species. He placed next the foregoing the Sigalion Mathilda of 

 Audouin and Edwards, for he thought they included two species under that title. He 

 entered the Sthenelais Idunx of Rathke, and the S. boa of: Johnston as separate species. 



Langerhans (1880) describes Sthenelais Idunse, from a depth of twenty fathoms off 

 Madeira. He points out the reddish colour of the head (from the brain), the ringed base of 



1 Op. cit., p. 463, fig. 12. 



