•JGli STEN0I)0>JT01’110H.VTK TEETH. 
Tlie Euthyneur.v or pulinonate species, the most highly si)ecialize(l 
of the Gastroi)oda, were all formerly relegated to the Cteiioglossa, 
a grou]) to which Clio, Actaum, Ihlichut, Limmco, Hdi.v and other 
terrestrial, Hnviatile and marine genera were also referred. 
^Vfter carefnl stndy and examination of many types, I have tenta- 
tively placed our Euthynenrons sjjecies in two chief divisions, 
Stenodontophora and Eurydontophora, based upon the more or less 
broad and (piadrate t>r narrow and sole-shaped form of the basal i)lates 
l)y which the teeth are attached to the lingual membrane. 
The Stexodontopiior.v ((rreros', narrow ; oSoih', tooth ; </)€/>w, to bear) 
are those species or genera with teeth (jf an 
aculeate character affixed to the radnlar 
membrane by a narrow and somewhat sole- 
shai)ed base of attachment, from the whole 
surtace of which there arises a strongly 
recurved spine-like tooth. 
'I'he surface of the radnla usually pre- 
sents a median and two marginal areas, and 
typically the teeth are uniform in character 
in each series, the nie<lian row, when i)resent, being sometimes formed 
by tritidly retlected teeth, and the 
marginals varying only in the size they 
attain, the largest and most powerful 
being placed near the outer margins, 
corresponding to tlie prominences of the 
lingual cartilage and the greater func- 
tional imi)ortance thus conferred by that 
l)0.sition in the seizure of i)rey, while those 
nearest the median line and the extreme 
marginals are the smallest, a gradual 
increase of size taking place from the 
median line and a much more rapid and decisive enlargement from 
the outer marginal series. 
It is the tyj)e of radnlar teeth for carnivorous mollu.sks and is 
characterized by comparatively limited series of long, narrow, 
loosely ranked spinous teeth, which apiu'oach the median line from 
the lateral margins at a posteriorly directed acute angle, as in 
TestaceUd ; hut in Plnjsa fontindlis the angle formed, although equally 
acute, points in the ojiposite direction. 
F' \c,. 531. — Section across the heail 
of Tcstncclla hnlloiidia Drap. , 
showing the form of the lingual car- 
tilage anti the disposition of the 
radnla, etc. (after Lacaze-Duthiers). 
7)1. matrix ; i.7)i. intrinsic muscles; 
7-.C. radnlar cartilage with superim- 
])oscd radnla. 
Fit;. 533. — Typical .\culeaie 
or Acanthoglossate tooth showing 
the sole-shaped base of attach- 
ment, highly magnified. 
