196 Proceedings of the Royal Physical Society. 
No. 6 represents the postero-lateral process, and is distinctly smaller 
on the left than on the right side. 
No. 7 represents the post-oral process, and is sometimes slightly smaller 
on the left than on the right side. 
I very much doubt whether Mortensen’s term “middle dorsal” process 
is strictly applicable to No. 4. The process in question clearly belongs to the 
anterior part of the larva, being well in front of the angle of the mouth, or 
region opposite to which the middle dorsal lobe or lappet is placed in the 
auricularian larva. While certainty on the matter will not be gained until 
the full development of the larva is known, it seems probable that Nos. 2, 3, 
and 4 are all subdivisions of the anterior dorsal process. Garstang’s figure 
(4, pl. xxviii. figs. 1, 2) of an intermediate stage shows this process divided into 
two. Probably the posterior of the two divisions becomes our No. 4, while 
the anterior division again becomes subdivided to form Nos. 2 and 3. Bury’s 
(2) similar larva from the Mediterranean has apparently only five ciliated 
processes on each side. More advanced but still relatively young Lucdia 
(sp.?) bipinnarize from Messina (kindly lent me by Dr Ashworth) all had the 
seven appendages just described, except in one instance where the first three 
were replaced on the right side by two short ones arising from a common base. 
Mortensen’s work on the early development of Luidia ciliaris only brings us 
to the stage when the bases of outgrowth of the ciliated processes are 
becoming evident. In Bipinnaria papillata (Miller 24, 1853) we have an 
instance in which the posterior dorsal process is pressed backwards towards 
the postero-lateral, while the anterior dorsal process is exceptionally large 
and has a base of unusual breadth (Mortensen 27, p. 44). 
Sars (26), and Koren and Danielssen (72) described the Sipinnaria 
asterigera (larva of Luidia sarsi) as having six ciliated appendages on each 
side in the neighbourhood of the mouth. Joh. Miiller (24, 1848, 1849) 
counted seven, his figure showing that the first two on the dorsal aspect 
arise from a common stalk. Garstang (4), from an examination of his 
relatively early larvie referred to above, believed Joh. Miiller to be mistaken. 
Mortensen (27, pp. 38, 59) established the correctness of Miller’s description 
and figures. . 
All the advanced bipinnarie, both of Lwidia ciliaris and L. sarsi, obtained 
by me in a condition suitable for examination exhibit a feature which does 
not seem to have been noted by any previous observer, namely, that the 
postero-lateral process on the left side is distinctly smaller than that on the 
right side, and indeed is occasionally little more than a short outfolding of 
the ciliated band. Not infrequently, also, the left post-oral process is 
