ZOOLOGY. 



the anterior part of the body of Lingula. The mouth is 

 bordered by two membranous, highly sensitive and movable 

 lips. The stomach is a simple dilatation of the alimentary 

 canal, into which empty the short ducts of the liver, which 



is composed of 

 masses of cceca. 

 The liver origi- 

 nally arises as 

 twodiverticula 

 or offshoots of 

 the stomach. 

 The short in- 

 testine ends in 

 a blind sac or 

 in a vent, and 

 is, with the 



i? ig. w. i i M i _ n 1 1 1 1 1 11 a i BC^LUJII \j\ LIU/ anttriiui jjui LIIMI ui "1 J* 1 



Linqula. m, mouth ; &>, oesophagus ; $/, stomach ; , arm ; ci, StOIliacn,ireeiy 



_ ; _ !._/ t _!__! i_ i J . _r *..!..; i_, _* . . ** 



suspended in 

 the peri visceral 



cavity by delicate membranes springing from the walls of the 

 body. (Fig. 99.) In those Brachiopods allied to Terebra- 

 iula, Terebratulina, Thecidium, Waldheimia, Rhynclionella, 

 etc., the stomach ends in a blind sac, and there is no vent,, 

 the rejectamenta escaping from the mouth. In Linyula and 

 Discina there is a vent which terminates anteriorly on the 

 right side. In Linyula 

 the intestine makes a 

 few turns, while in Dis- 

 cina it makes a single 



st ce cf) m 



Fig. 98. Longitudinal section of the anterior portion of 



la. m, mouth ; a>, ffisophau* ; sf, stomach ; o. arm 

 cirri ; bf. brachial told ; cf>, cartilaginous base of arm 

 sinus leading to the arm ; cc, cephalic collar or pallial mem- 

 brane. After Morse. 



turn to the right. 



The nervous system 

 consists of two small 

 ganglia above, and an 

 infracesophageal pair of 

 larger ganglia, and there 

 are two elongated ganglia behind the arms, from which nerves 

 are given off to the dorsal or anterior lobe of the mantle. 

 From the infraoesophageal ganglia two lateral ventral cords 

 pass backwards, in their tract sending off delicate threads, 



Fig. 99. Transverse section of TAngitJa. f>, 

 bands suspending the intestine in the perivisce- 

 ral cavity ; i, intestine ; ., segment al organ ; o, 

 ovaries ; I, liver ; g, gills ; ,<?, setae. After 

 Morse. 



