536 Mr. B. B. Woodward on the Forward Progression 
Batrachoides cryptocentrus, Cuv. & Val. 
Depth of body 43 to 54 in the length, length of head 
3 to 81, width of head between opercles 3} to 3. Diameter 
of eye 5 to 6 in length of head, equal to or slightly less 
than interorbital width. One subopercular and two oper- 
cular spines. Maxillary extending beyond eye. Lower jaw 
a little projecting. ‘leeth on vomer and _ palatines large, 
uniserial, obtusely conical; 4 on vomer, 10 to 13 on each 
palatine; lower jaw with a single series of similar teeth, 
and anteriorly a patch of sharper teeth; premaxillaries 
with two rows of villiform teeth. Head and body entirely 
naked; head covered with small filaments, that above 
the eye well developed. Snout with a fringe of fila- 
ments; another fringe on lower jaw, four of which are 
distinctly larger than the remainder. Irom above and below 
base of pectoral two rows of open pores, appearing as white 
spots, which become indistinct in the adult, extend backward 
nearly to end of soft dorsal and anal respectively. Dorsal 
I1I 26-28 ; spines short, almost entirely hidden under the 
skin. Anal 22. Pectoral 21; a pigmented patch in the 
axil, but no foramen Caudal 18, rounded. Brownish, 
paler below, with traces of darker vertical bands, disappear- 
ing in the adult; fins edged with darker. In young and 
half-grown individuais the throat is marbled with pale 
irregular spots. 
Three specimens, 70-220 mm. in total length. 
LXI.—-Note on the Forward Progression in its Shell of the 
Animal of the Nautiloidea and Ammonoidea. Compiled 
from Notes left by the late G. C. Crick, F.G.S., by B. B. 
Woopwarp, F.L.S. 
Tue three facts which are necessary to remember when 
attempting to form a conception of the mode of growth in 
the Nautiloidea and Ammonoidea are :—- 
(1) Growth in bulk of the animal taking place at regular 
intervals, terminated respectively by the formation 
of a new septum. 
(2) Rigidity of the shell, necessitating a forward movement 
of the too bulky animal. 
(3) Faculty of secreting gas, which must not be allowed to 
escape from the chambers of the shell. 
