On a New Brachiate Asteroid Larva. 191 
XXIV.—On a New Brachiate Asteroid Larva and on the Advanced 
Bipinnaria of Luidia ciliaris (Philippi) Gray. By James F. 
Gemmill, M.A., M.D., D.Sc. 
(With Plate.) 
(Read 21st December 1914. MS. received 25th January 1915.) 
I. Brachiolaria hibernica, n. sp. 
BRACHIA, stout, columnar, with very slightly convex ends, each of which 
carries about twenty papille ; sucker much elongated transversely ; a single 
row of six or seven papille to each side of the sucker; no papille on sides of 
brachia; ciliated processes cylindrical at extremities. 
Locality of Occuwrrence.—50 miles N. by W. of Eagle Island, West of 
Ireland, taken in net drawn up from 1150 fathoms to surface. 
Only one specimen of this highly interesting brachiolaria was obtained, 
but several Lwidia sarsi bipinnariz were caught in the same tow-netting, and 
probably all occurred relatively near the surface. It will be inferred from 
Pl. VL, Figs. 1 and 2, that the specimen is undergoing the retraction changes 
characteristic of early metamorphosis in larve with indirect development 
(see 6, pp. 251-253 and pls. xx. and xxi. figs. 12-14). We are not, therefore, 
in a position to speak definitely regarding the appearance of the uncontracted 
free-swimming larva, but in all probability it conformed to the type exempli- 
fied in the life-history of Asterias rubens L. (see 6, pls. xix., xx. figs. 10-12). 
The retraction changes referred to above cause the preoral and middle 
regions of the larva to be drawn towards and finally incorporated with the 
left (future oral) aspect of the posterior or disc portion of the larval body. 
The mesenchymatous tissues of the regions undergoing shrinkage break down 
and are transferred in a semi-fluid condition to the disc, much of their debris 
being ultimately swallowed by the cells lining the hypoblastic tube, the wall 
of which becomes syncytial and greatly thickened. At the same time the 
larval mouth and anus undergo closure. Normally in the case of brachiate 
larvee, prior to the changes in question, fixation has been effected, first 
(temporarily ) by the brachia and afterwards (definitively) by the sucker. Some- 
times, if larvee have not the chance of attaching themselves, or fail to effect 
attachment, the retraction processes are nevertheless initiated. In such cases, 
normal metamorphosis does not appear to be possible in dA. rubens, but 
according to Goto (8) it can readily occur in A. vulgaris. In our specimen 
