76 



Y.I. KANTOR, A. MEDINSKAYA AND J.D. TAYLOR 



Fig. 22 Ptychobela suturalis (Gray, 1838). A, semidiagrammatic longitudinal section of the foregut (only one salivary duct shown) with the proboscis in 

 an everted position and buccal lips inverted inside the buccal cavity; B, longitudinal section of the proboscis tip. 



The proboscis walls are medium-thick, and comprise about 15% 

 of the proboscis diameter. The mouth is narrow in relaxed animals, 

 but capable of great expansion. The muscles of the proboscis walls 

 are equally developed along its length. 



The buccal tube has a very small anterior sphincter and there is no 

 sac-like enlargement at the distal end There is large intermediate 

 sphincter, which lies about two radular tooth lengths behind the 

 proboscis tip. The buccal tube has rather thick walls, only slightly 

 thinner than those of the proboscis. In the anterior half of the 

 proboscis, the buccal tube is narrow, but greatly expanded posteriorly. 

 There are large, extensible buccal lips which can invert into the 

 buccal cavity. In retracted specimens, they form a muscular tube 

 with a flaring aperture, which extends beyond the mouth of the 

 proboscis. 



Buccal mass and oesophagus 



The buccal mass lies within the base of the proboscis, and is rather 

 long, comprising about a quarter of the proboscis length, with 

 relatively thin walls and a very broad inner cavity, which is not 

 curved. The oesophagus is elongated between the buccal mass and 

 nerve ring, forming the short loop. 



Glands 



The salivary glands are large, paired and acinous. The venom gland 

 changes in histology after passing anteriorly through the nerve ring. 

 The duct of the gland is narrow, ciliated, and opens into posterior 



part of the buccal cavity. The muscular bulb is long, with the wall 

 formed of two equally thick layers of longitudinal muscle fibres, 

 divided by a connective tissue layer and very thin innermost layer of 

 circular fibres. 



Odontophore and radula 



The odontophore is small with the odontophoral cartilages, paired, 

 and unfused. The buccal sac is very short. The radular teeth (Fig. 

 23a) are hollow and awl-shaped with a sharp point and broadening 

 towards the base. They are composed of two separate pieces which 

 are fused along one edge and loosely twisted together. 



Cheungbeia mindanensis (Smith, 1877) 



(Figs 24, 26d, 30d) 



See also Taylor (1994, plates lh, 6d; figs 13-15) 



Rhynchodeum and proboscis 



The rhynchodeal sphincter is large and anteriorly located and the 

 rhynchostome is relatively wide. The epithelium of the anterior half 

 of the dorsal wall of the rhynchodeal cavity is glandular (dorsal wall 

 is significantly longer than the ventral). In the posterior part of the 

 rhynchodeum the epithelium is non-glandular and continuous with 

 that of the proboscis wall. The proboscis is extremely long and lies 

 coiled within the rhynchocoel.The proboscis walls are highly folded 

 and comprise about 15% of the proboscis diameter. The muscles of 





