ON THE ACEPHALA. 371 



B. cASTANEus, Alder and Hancock. 



" General envelope very thin and pellucid, with a few scattered 

 brown marks and black punctures on the margin. Individuals 

 large, placed in irregular circles of from six to eight, of a chestnut 

 colour, irregularly blotched with purple brown, and minutely 

 sprinkled with opaque white. Branchial aperture small, general 

 aperture moderate. Stars rather far apart, and surrounded with 

 a few large opaque yellowish-white globular bodies. 



"On the under side of stones, in pools, between tide-marks, 

 Cullercoats, rare. 



" The envelope of this species is thinner than in any other we 

 are acquainted with, and, when removed from the stone, is 

 extremely flaccid. The patches are large, being sometimes five 

 inches across." — Ald. Cat. p. 111. 



BoTRYLLoiDEs RADiATA, Alder and Hancock. 



" General envelope yellowish - olive, with yellow granules. 

 Individuals rather small, broadly pear-shaped, pale ochreous 

 yellow or straw-colour, spotted with white, and having a paler 

 rim round the branchial aperture, with rays diverging from 

 it and uniting into a disc beyond, giving a petaloid or wheel-like 

 appearance to it. A darkish line runs down the thorax. The 

 systems are arranged in much shorter and more compact folds 

 than in the last ; some parts occasionally assuming the appear- 

 ance of a circular arrangement. The common apertures are 

 usually situated at no great distance from each other. 



" On the under side of stones, among the rocks at Cullercoats 

 and Whitley, frequent. 



" The smaller size, more varied markings, and shorter and 

 more rounded convolutions, distinguish this species from the last. 

 The wheel-like markings ally it to the B. rotifera of Milne- 

 Edwards, but the colour never approaches to red, and the folds of 

 B. rotifera appear more elongated than in ours. In this respect 

 our species approaches more nearly to the arrangement of B. 

 albicans.'''' — Ald. Cat. p. 112. 



