No. 478] ODOXrOPHORAL APPARATUS IN SYCOTYPUS 735 



and if it acts as a blood sinus, tliere is litde difficulty in explaining 

 how the prol)oscis is pushed out by hydrostatic {)ressure. 



The results of the present iiu cMipuion may be summed up as 

 follows: — 



The odontophoral apparatus in Sycotyjiiis is liiohly (•()ni])lex, 

 but admiral)ly adapted to its function. 



The mechanism of the radula, in Sycotypiis ;it iiiiy nite, is 

 correctly termed, after Huxley, a chain saw, with the restriction 



The buccal cart ihiuv, besides formino- a slillVninir framework, 

 acts as a o-rooved pathway alon^^ which tlie radular sac and the 

 great retractor of the dental ribbon slide, the path bein^; well 

 lubricated, probably by a mucous ^ecretion. In Sya)typus the 

 cartilage is passive, so far as any licking action is concerned. 

 The buccal cartilage ])()ssesscs its own nniscles for ])r()(raction 

 and retraction, as well a^ <rrtai.i tnuM \v> iliar l.in.l it^ rami tngriher 

 and at the same thnc form a d.caih tor lUr n'ira.-tor of ihr radula. 



The radula is ])rotractcd, /. r., .Iraun foruanl. 1.x h\ dnxler 

 muscles, four of which (two pairs i ii(- along die \. -rural m.Ic of the 

 rami of the buccal cartilage cn(io>f(l within coinifctn c-n.^Mic 

 sheaths; the other pair lie along the mi.l-\fiiiral iin.-of th." huccal 



