SOFT PARTS AND MECHANISM OF THE PROBOSCIS. 395 
appearance first described by Anthony* and subsequently 
independently by Wright+ as suckers; each appears as if 
closed by a thin membrane. 
In Anthony’s figure these membranes are represented pro- 
truding as sucker-like organs which he described as having the 
appearance of ‘ mouse ears,’ or ‘ bat’s ears.’ I have observed a 
similar appearance in surface views of the oral disc of the 
proboscis, but more commonly these so-called suckers appear 
as they do in Wright’s photograph (Pl. XXIII., Fig 2). 
Sections of the oral lobes throw light on the true nature of 
these ‘suckers.’ Fig. 50 (3 and 4) shows the disposition of the 
thin cuticle between the fork of a ring; it forms a little sac (s) 
by the side of the pseudo-tracheal channel. Now, it is mani- 
fest that such a sac would be easily everted, and it would then 
present the appearance described by Anthony ; or, if partially 
everted, the appearance shown in Wright’s photograph. 
Between the pseudo-trachez, and covered by inflections of 
the hypodermis, a series of tendinous cords extend from the 
discal sclerite to the edge of the oral disc. These tendinous 
cords were first described by me [62, p. 49], but perhaps rather 
indefinitely. Kraepelin describes and figures them. 
These cords are dissolved by boiling caustic potash, but do 
not seem to be affected by dilute acetic acid; they are de- 
veloped from fusiform cells. The paraphysal muscles are 
inserted into them near their origin, so that they are probably 
inelastic and act as tendons. 
ce. The Mechanism by which the Proboscis is Extended and 
Erected. 
It is quite certain that the retraction of the proboscis and the 
movements of the haustellum upon the rostrum are muscular 
acts, but it is also very evident that there are no muscles 
capable of exserting the proboscis. This fact has already been 
noticed by Gleichen [8], Macloskie [64], Dimmock [68], and 
* Monthly Micros. Journ., vol. xi., p. 242, 1874. 
t Journ. Royal Micros. Soc., ser. ii., vol. iv., p. 1003, 1884. 
