374 Mr. L. Reeve on the Re-calcification of the Shell in Cypreea. 
If therefore no specimen of Z. Blochii exists exceeding 13 ft. in 
length, little doubt can remain that this species is Z. daticeps in 
its foetal or very young state. 
In the principal part of this paper, viz. in the remarks on the 
identity of Sphyrna Blochii with the foetal state of /aticeps, Dr. Cantor 
has been forestalled by Miiller and Henle, who quote Dr. Cantor’s 
Zygena laticeps as a synonym of their Sphyrna Blochii. In another 
point noticed in the commencement of the paper, viz. the identity of 
the Koma sorra of Russell with the Zygena Tudes of Valenciennes, 
Dr. Cantor differs from Muller and Henle, who refer Russell’s figure 
to the Sphyrna Zygena or the malleus of Valenciennes, and their 
authority is deservedly the highest as to Malacopterygian fish. ‘The 
fact however of the foetal fish with the head doubled back being 
taken from the mother shark with the long transverse head of Jlati- 
ceps is worth recording, as is also the habitat, for the range of 
Sphyrna Blochii is not well known.—J. R. 
XLI.—On the Dissolution and Re-calcification of the Shell in 
Cypraea, a genus of Pectinibranchiate Mollusca. By Lovuu. 
Reeve, A.L.S. &c.* 
Tur formation of a new shell in the Cowry at an advanced period 
of its existence is a pheenomenon which modern naturalists have 
hesitated to receive. Bruguiére first introduced the fact, but in 
a manner which appeared to savour of the marvellous ; and even 
Lamarck says, “I possess observations which tend to prove that 
the Cowry, arrived at the power of forming a complete shell, has 
still the faculty of enlarging its habitation, and is then obliged 
to quit the shell in order to form a new one. It results from 
this, that the same individual has the power of forming a suc- 
cessive number of shells during both the second and third stages 
of growth; and which accounts for our often meeting with so many 
different sizes of the same speciest ” ! 
M. Deshayes, after furnishing us with an excellent account of 
the zoological characters of Cyprea, derived mainly from the ob- 
servations of MM. Quoy and Gaimard (Zoologie, Voyage de 
V Astrolabe), argues against the possibility of any re-modelling of 
the shell taking place, and regards the statement of Lamarck as 
a theory opposed to the common laws of organization. To the 
supposition of Bruguiére that the Cowries cast their shells after 
the manner of Crabs, M. Deshayes very properly replies, that 
there can be no analogy between them. ‘The new shell of the 
Crustacea is formed by a secretion of equal consistency from 
* Written for a forthcoming monograph of the genus Cyprea in the 
‘ Conchologia Iconica,’ and communicated by the author. 
+ Animaux sans Vertébres (Deshayes’ edit.), vol. x. p. 482. 
