139° 
tooth-bearing process of the piston cartilage. In action it appears to 
pull the piston cartilage backwards somewhat and at the same time 
to press it against the lower border of the anular cartilage. Another 
small sheet of muscle (XIX), of which I have no record in my notes 
of P. FÜRBRINGER, is that which ventrally is inserted into the inner border 
of the pedicle (anterior dorsal) along its whole length and dorsally is 
attached to the dorsal anterior edge of the posterior lateral cartilage. 
This muscle may appropriately be called the rhombo-semianularis.’) 
t ‘ 
Maxillary Nerve a 
Fig. 21. 
i Oesophagus ¢ 
fr Sere iory, 
mber 
in 
ix: Ye 
= 
‘ we = = 
7 i A 
7 
Fig. AR. 
Fig. 21 (X cire. 1). Further lateral dissection of Geotria australis. The 
basilaris muscle has been removed, also X, IX, the median portions of XVI and 
X] and the dorsal portion of VIII. XII has been turned down. 
Fig. 22 (X eirc. 1). In this figure the branchial basket, gill pouches and 
muscles have been removed, also XIV, XV, XII, XVI, XI, XIX and XX, and 
the posterior lateral cartilage. The piston cartilage has been thrust forwards, 
Fig. 23 (x eire. 1). Attachments of the semianularis muscle. 
Fig. 24 (X cire. 1). Ventral view of the muscles XXII and XXIII, the 
piston cartilage having been turned ventrally and then forwards and XIII slit along 
the mid-ventral line and the halves turned dorsally. 
1) I am uncertain about the existence of this muscle. 
