PROBOSCIS. 



65 



which have been kept some hours in water, and then placed under pressure. The ruptured fibres 

 keep jerking and twisting in a very characteristic manner, the free margin of the organ being 

 fringed with coils. 



The anterior region of the proboscis in Ampkiporus bioculatus is faintly pinkish, and the 

 glands rather numerous and small. The basal apparatus of the stylet-region (Plate XXIII, fig. 19, 

 and woodcuts, figs. 3 and 4), is much elongated, rather wide anteriorly, so as to have a nearly 

 uniform diameter throughout, and rounded posteriorly. The constituent opaque- white granules 

 are minute, while the head of the stylet is large. The muscular cavity (<■) behind the floor of 

 the anterior chamber is small, and obscured by the external granular glands, for the latter extend 

 both before and behind the basal apparatus under pressure. The other parts of the organ 



Pig. 4. 



Pig. 5. 



o 



Central apparatus of the stylet-region 

 of A. bioculatus. x 220 diam. 



Isolated stylet. 

 X 220 diam. 



Central apparatus of the stylet-region of 

 Tetrastemma Hobertiance,. x 350 diam. 



presented no noteworthy feature, except that no circular coat could be made out in the anterior 

 region between the greater longitudinal and the mucous coats. 



In Tetrastemma melanocepkala the proboscis is somewhat larger than in A. lactifloreus ; and 

 exhibits certain important differences. The stylet-region (Plate XII, fig. 8) has the marginal 

 sacs carried considerably forward, so that they lie quite in front of the central apparatus, 

 and the floor of the anterior chamber has consequently to form a deep pit to reach the spike of 

 the central stylet. The basal apparatus of the latter is proportionally large, while its wedge- 

 shaped investment is comparatively meagre. The radiating or oblique fibres (near 0) which 

 pass outward and forward from the latter, in the usual position of the organ under pressure, 

 are very distinctly shown, and apparently sling the apparatus. The points of both central and 

 marginal stylets (Plate XIV, figs. 8 and 9) are rather blunt, and their shape on the whole 

 resembles that in T. Candida. The circlet of granular glands is much developed, and often renders 

 the subjacent parts obscure. 



The remarks and figures of M. de Quatrefages relating to this species (his Folia coronata) 

 require amendment. He mentions that it is the only exception he has met with to the uniform 



9 



