74 THE LINGULIDA OF THE QUEENSLAND COAST. 
The anterior occlusors (central muscles of King and 
Davidson), as seen on removing the dorsal valve, are rela- 
tively larger and more distin tly pyriform than they are in 
‘L. anatina, while the anteriorly directed narrow portion of 
each approximates its fellow so that a very narrow interval 
separates them from each other and from the hinder border 
of the lateralis muscles (anterior laterals of King and David- 
son). These anterior occlusors are relatively larger than 
those of L. lepidula (Morse, pl. 48, fig. 2) and of about the 
same relative size as those of L. affinis, but they approach 
each other more closely in L. bancrofti than in the last- 
named species. The lateralis is relatively smaller than in 
L. anatina (Hancock, Woodward, King) and L. lepidula 
(Morse). The posterior occlusor (umbonal) muscle is well 
developed and is circular or elliptical in outline. 
If the ventral valve be removed the appearance of the 
muscular system is somewhat like that figured by Hancock 
(pl. 64, fig. 2) for his L. anatina (whichis really L. murphiana) 
except that the posterior lateral pallial region is much 
narrower and the lateralis better deve’oped in L. bancroftt. 
In the latter the internal oblique (transmedian of King 
and Davidson) is more powerful and covers the posterior 
parts of the nephridium, while the anteriorly situated band 
of its divided fellow of the opposite side is considerably 
wider than the posteriorly directed portion, reminding one 
of the condition figured by Gratiolet (p. 77, fig. 11) for L. 
anatina, and by Morse (pl. 48, fig. 2) for L. lepidula. In 
L. affinis they are subequal (Hancock, pl. 65, fig. 2). 
The mouth, an elongate aperture with a _ crenate 
border, leads into an cesophagus which is thick walled, 
especially near the mouth and in the vicinity of the insert- 
ion of the mesentery. The stomach is more marked than 
in Hancock’s figure (pl. 65, fig. 4) but less pronounced than 
in L. lepidula (Morse pl. 47, figs. 5 and 6). The gastric 
or stomachal glands (“‘ liver ’’ or hepatic diverticula) occupy 
a great deal of the perivisceral ccelome, the dorsal portion 
being more extensive than the ventral. The straight 
intestine proceeds posteriorly in line with the cesophagus 
and stomach, but just in front of the umbonal muscle it 
becomes bent forwards on the left side sometimes reaching 
