634 R. C. PUNNETT. 
No. of Specimen. 
(1) (2) (3) (4) (5) (6) (7) (8) 
Length of; collar’... .:...c0c--++<. 3 3 3 2°5 2°5 2°5 15 — 
5 yy PYODOSCIS .....se.00ee 55 6 5 5 45 4:5 4 _ 
i », branchial region ... 20 17 16 17 175 17 10°5 9 
Motal@lenp thy .ceseecsseceseaseances — 215 — — — — — — 
Branchial length 
Collar length 
No of illWslitsicrssc-cscdeeseens 116 — 110 104 102 88 74 58 
veconcorcoar eeeeee 66 56 53 68 7 6:8 a — 
The ‘specimens are given in order of size, (1) being the largest, (8) the smallest. 
In his account Willey states that external liver saccules are not present in the allied 
species S. alba (99, p. 277), “although, when fresh, the annular ridges were found to be 
turgid and to present the appearance of rudimentary saccules, an appearance which was 
almost entirely lost after preservation.” He was unable to state anything with regard to 
this region in Sp. porosa as his only well-preserved specimen lacked the post-genital portion 
of the body. External liver saccules are nevertheless present in Sp. porosa, though they are 
not very prominent (Pl. XXXIX. fig. 13). That they project somewhat from the dorsal 
surface may be more readily seen in transverse sections (see Pl. XLI. fig. 5). They are 
also characterized by their green colour, 
\ 
Re - 

l 
ye 
sg mm 

Fic. 120. Schematic reconstruction of anterior end of Sp. porosa, x 10. The dotted line in front of the stomochord 
indicates the forward extension of the pericardial auricles. For lettering see p. 676. 
INTERNAL STRUCTURE. To the full and careful account given by Willey I have little 
to add, and that chiefly in regard to the post-genital region which, as has already been 
mentioned, was absent in his specimen. 
Proboscis. In Willey’s specimen the ventral recurrent vessel was independent of the 
ventral septum. In the three specimens which I have examined it runs up to the central 
complex in the anterior free edge of the ventral septum (Text-fig. 120, vrv.). 
Willey states that the median muscular system extends over about 4+ of the length 
of the proboscis. It is not quite so long in the Maldive forms and may be exceedingly 
short (Text-fig. 120, mdv.), not extending quite so far forwards as the pericardial auricles. 
