646 R. C. PUNNETT. 
(Pl. XLVI. fig. 48), springing from low down. The branchial division of the cesophagus is 
somewhat more capacious than the ventral division of the cesophagus. The number of 
synapticula on the longest gill bars is either 7 or 8. 
Ptychodera flava, var. laccadivensis (Pl. XXXIX. fig. 25; Pl. XL. figs. 36, 38—40: 
Pl. XLV. fig. 43; Pl. XLVI. figs. 49, 51, 57). 
Locauity, ETc. Muinikoi; from lagoon close to edge of lagoon flat. It occurred in 4 
feet of water at low spring tides and was very abundant. The followmg notes were made 
by Mr Gardiner. 
“A few points about them are of interest, viz. (a) The tail part of the body, ie. 
posterior 1, is merely a bag of sand and is often broken off if the animal be held still 
by the head end. Under these circumstances the sand appears to be driven back by peri- 
staltic movements of the whole body-wall more rapidly than it can escape, and as a result 
the posterior end simply breaks off. This I have verified by repeated observations under 
water and I believe that it occurs im life. (b) In distribution they are limited to the 
weed and to an area close to the edge of the flat. (c) Their natural position when alive 
is within 4 inches of the surface of the sand. The head is close to the surface whilst 
the body and tail are horizontal. (d) When thrown on to a sandy bottom the motion is 
very feeble or nil if the body be full of sand. The posterior part is at once dehisced. A 
wriggling motion of the branchial and genital regions ensues, accompanied by powerful con- 
tractions of the collar and extensions of the proboscis. The proboscis and collar! are very 
slowly forced into the sand and then the body follows with comparative rapidity.” 
EXTERNAL FEATURES. This variety shews a great resemblance to Pt. flava, var. cale- 
doniensis (Willey, 799, p. 228) in general appearance. The largest complete specimens which 
reached me are about 150 mm. in length, but fragments of larger specimens point to its 
attaining a somewhat greater size. The proboscis is cf about the same length as the collar 
or slightly longer. The anterior liver saccules are dark, the posterior lighter in colour. The 
larger liver saccules are lobulated along one edge, such lobulation being most marked in 
the larger specimens. The length of the branchial and post-branchial genital regions are 
dealt with later (p. 663) in connection with variation in the group. The colour of the 
animal in life was bright yellow or pale lemon, thus differing somewhat from Pt. caledoniensis, 
which is of a duller hue inclining to brownish. 
INTERNAL STRUCTURE. 
Proboscis. Just beneath the basement-membrane occur a few delicate circular fibres 
surrounding the longitudinal muscles which are gathered up into radial bundles. These 
bundles project into the proboscis coelom, which has no well-defined boundary (Pl. XXXIX. 
fig. 25). Dorso-ventral muscles are usually to be found in the region of the central complex. 
The ventral proboscis septum extends forwards as far as the tip of the stomochord. The 
decussation of muscle fibres on the dorsal side of the anterior portion of the proboscis is 
well-marked as a rule, and a few circular fibres may be continued from it round the inner 
edge of the longitudinal muscles on the ventral surface of the proboscis cavity. The proboscis 
coelom of both sides may be placed in communication with the exterior by the two proboscis 
pores. It as often happens however that the communication between the proboscis coelom 
1In Dolichoglossus pusillus, whose movements form the subject of a paper by Ritter (02), the proboscis appears 
to play a relatively more important part. 
