PLATE IX. 



Fiii. .S2.- — Alimentary canal opened alon^ the (lnr«d side. ^Natural s-ize. 

 Al', anterior prelin^nal prot-et^s. 

 BJI, buccal niend)rane. 

 C, ciecum, showini!; its ])rojectiiig ianielUe. 

 HI), ojienings of tlie hepatic ducts into the cuecuiu. 

 LJ, lower jaw. 

 M!\I, mandibular iiuiscle. 

 Oe, o'sophagus. 



PP, posterior iirelingual jjroce.'^s. 

 I'r, proventriculus. 

 K, radula. 

 Uc, rectum. 



iS, saccular posterior ])ortion of tlic stomach. 

 SO, .sali\arv jiore. 

 SP, salivary jirocess. 

 T, tentacles of the stonuK'h. 

 Tn, tonsrue. 

 IM, upjier jaw. 

 V, vestiliule. 

 X, ainiarently permanent ridges of the a;-sophagus. 



1, 1, intestinal ridge. 



2, intestinal ridge. 

 :i, 3, intestinal ridge. 

 4, foliaceous ridge. 



Fii;. 3.'). — Ventral view of the buccal mass, a portinn of its nmscnlar membrane having been folded back. X 2. 

 Bd, f)uccal ganglion. 



BM, liuccal memlirane, cut and turned forwnnl over the li|i of the jaw. 

 L.T, outer tlange of the lower jaw. 

 LM, levator muscle of'the buccal mass. 

 ■ M, mandibular nuisele; this ends ventrally along the edge of the upper jaw. 

 BIM, nuiscular membrane of the buccal ma.ss. 

 K', outer cereliro-l>uccal connective. 

 N'^, inner cereliro-liuccal coiniective. 

 Oe. M, meudirane snrronnding the base of the o'sophagus ami ci)nnecting with the membrane surrounding 



the central nervous system. 

 OM, part of the membrane stretclied between the ventral Imccal retractors. 

 l'h.(_i, pharyngeal ganglion. 

 RL, ligament of tlie radularsac. 

 KS, radular sac. 

 VI5K, ventral buccal retractor muscle. 



1, retractor of the anterior prelingual process. 



2, retractoi' of the posterior jirelingnal process. 



.3, :-!, unpaired nuiscle, forked posteriorly, going to the posterior prelingual process. 



4, muscle extending into the posterior prelingual iirocess, and also to the portion of the tongue anterior to the 



upwardly directed part of the radular sac. 



.'), iimscle to the anterior ])ortion of the tongue. 



(>, nuiscle to the membrane covering the iirojection of the upper jaw. 



7, muscleto the dor.-^al surface of the radular sac. 



K, Muscle which probaldy plays a share, at least, in the ojieuing of the jaws. 



!>, origins of nuiscl(>s 1, 2,' 7, upon the inner surface of the muscular membrane. 

 Fio. :!4. — Dorsal view of the buccal ma.'^s, the enveloi)ing muscular membraue having been cut along the median line. 

 The view is al.-^o .somewhat from liehind. X 2. 



A, branches of the suijerior mandiliular artery jienetrafing the mandibular nmscles. 



I5M, buccal uiembraue, also slit open dorsally. 



Ij.7, tip of lower jaw. 



M, mandibular nuiscle. 



M.M, nuiscular membrane of the Iniccal mass. 



(.)e, a'.sophagus. swollen at one i)lace by food wliicli remained in ii wlicn tlie animal died. 



r,r, tip of the upiier jaw. 



r.T, posterior edge of the inner flange of the upper jaw. 

 Fio. 35.— The radular sac and the lingual muscles of one side exi)osed an.l vieweil from llie ventral side. X 2. 



KL, external lingual muscle. 



EI/, cut entl of the external lingual muscle. 

 - IL, internal lingual muscle. 



LP, lingual |)rotractor muscle. 



K, radular muscle. 



K' i-ut end of tlu' radular muscle. 



Ka, radula. 



H8, radular sac. 



5, septum extending from the dorsal median line of the tongue to the muscular membrane just above tne 



ra<1uhir sac, wliich has been cut away from the exposed side of the jireparation. 

 T, tendinous area where the lingual muscles join. 

 X. division of the septum. 

 Y. point of the upper jaw to which the lingual protractor is attached. 



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