138 
The hyoglossus (XI/) is a sheet of muscle which, as just stated, is 
confluent posteriorly with the two muscles just mentioned. Anteriorly 
it is obliquely divided into two portions—a postero-dorsal and an 
antero-ventral—by a cleft (not shown in the figure) running antero- 
posteriorly and dorso-ventrally. The antero-ventral portion is connected 
dorsally by means of a stout tendon with the fascia of the basilaris 
on its ventro-lateral surface, as shown in the figure (see also fig. 24 
in which the tendon has been cut through and the muscle turned 
down); the postero-dorsal portion is connected dorsally with the piston 
cartilage anteriorly and with the base of the styloid process posteriorly 
(not shown in figure). As already mentioned the portion of the 
muscle posterior to the cleft is attached to the piston cartilage in 
confluence with the anulo-glossus and copulo-glossus rectus. The 
hyo-hyoideus posterior (XIII), hyo-hyoideus anterior (XIV), hyo- 
branchialis (XV), spinoso-copularis (XVII) and copulo-glossus obli- 
quus (XVIII) muscles, portions of which are shown in figure 20, 
will be described in later figures. 
In the further lateral dissection of Geotria shown in figure 21, the 
basilaris muscle of this side has been removed, also the latero-semianularis 
(X) and the spinoso-semianularis posterior (IX), the median portions | 
of the anulo-glossus (XV J) and copuloglossus rectus (XI) and the dorsal 
portion of the spinoso-semianularis anterior (VIII). The antero-ventral 
portion of the hyoglossus (XII) has been turned down. The spinoso- 
copularis muscle (XVII) is now visible. It isasmall flat sheet of muscle 
of the form of an inverted triangle, one side ofthe triangle being attached 
dorsally to the lower edge of the styliform cartilage and the opposite 
angle to the dorsal side of the lateral extremity of the median ventral 
cartilage (M.V.). The function of this small muscle is to depress the 
styliform cartilage and is thus antagonistic in action to the two spinoso- 
semianularis muscles. P. FÜRBRINGER states that when all these three 
muscles work simultaneously the result is the pushing forwards of the 
anular cartilage, and from this standpoint these three muscles col- 
lectively are antagonistic to the anulo-glossus. Immediately behind 
the spinoso-copularis muscle, there will be seen in figure 21 the 
lateral portion of the copuloglossus obliquus muscle (XVJIJ). This 
is a relatively small strip of muscle inserted ventrally in the mid- 
ventral line into the lower median surface of the median ventral 
cartilage; it then runs outwards and upwards and forwards and ends 
in a long tendon which is inserted into the hind surface of the dorsal 
