Miscellaneous. 143 
The ‘* Crag Mollusca.” 
In the last number of the ‘Annals’ Mr. Searles V. Wood ex- 
pressed his opinion that Purpura tetragona of his late father’s 
Monograph on the Crag Mollusca was a variety of Murea erinaceus, 
and not of Purpura lapillus, in which Prof. Prestwich placed it on 
my authority, in his papers on the Crag beds of Norfolk and Suffolk. 
This question involves a difference not merely of a specific but of a 
generic and even family character. In Murew the canal is of 
moderate length, and is more or less covered over or closed above ; in 
Purpura the canal is very short and quite open. All the specimens 
which I have seen of Purpura tetragona, including the types in the 
British Museum, belong (as I consider) to the latter genus, in which 
Mr. Wood’s father properly placed it. Some Crag specimens of Pur- 
pura lapillus are carinated, and others are more or less cancellated, 
as in the variety tetragona. The sculpture of Murewv erinaceus is 
different. I may observe that the specific or varietal name tetra- 
gona ought not to be accentuated like the English word “ tetragonal,” 
but that the penultimate syllable is long, as in the Latin word 
“ tetragonus.” 
J. Gwyn JEFFREYs. 
On a new Crinoid from the Southern Sea. By P. Herserr 
Carpenter, M.A., Assistant Master at Eton College. 
Among the collections of the late Sir Wyville Thomson a small 
Comatula has recently been discovered which was dredged by the 
‘Challenger’ at a depth of 1800 fathoms in the Southern Sea. 
Although it is unusually small, the diameter of the calyx being only 
2 millim., the characters presented by this form are such as to 
render it by far the most remarkable among all the types of recent 
Crinoids, whether stalked or free. The name proposed for it is 
Thaumatocrinus renovatus. 
It has only five arms, and in this respect resembles Hudiocrinus. 
But the basals, instead of becoming transformed into a rosette as in 
that genus, persist on the exterior of the calyx, and form a closed 
ring of relatively large plates, which rest upon the centrodorsal. 
They support a ring of ten plates, five of which, alternating with 
the basals, bear the arms, and are therefore the radials. These 
radials, however, do not meet one another laterally ; for they alter- 
nate with five plates slightly smaller than themselves, which rest 
upon the basals, and, with one exception, terminate in a free edge 
at the margin of the disk. The exception is the interradial of the 
anal side, which bears a short and tapering arm-like appendage of 
five or six joints. It has no special relation to the anal tube, the 
lower part of which, like the peripheral portion of the disk, bears a 
pavement of anambulacral plates. But the centre of the disk is 
occupied by a relatively large and substantial oral pyramid ; so that 
the disk in its general aspect resembles that of Hyocrinus. 
