156 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 
and furnished with adhesive papille posteriorly, tapers 
eradually forwards from the hinder fourth of its length. 
Reticular black pigment was present only between the 
eyes. The character which especially distinguishes this 
species is the copulatory organ (fig. 9). This consists of a 
fine chitinous tube coiled in the manner of a bishop’s 
crozier. ‘This tube is enclosed in an outer muscular one 
which transmits the spermatozoa, the inner chitinous duct 
containing the secretion of the accessory or granule-gland. 
The form of the copulatory-organ among Turbellaria 
has been much used for the discrimination and determin- 
ation of species in this group. It is therefore interesting 
to find in different individuals of Promesostoma marmora- 
tum, an amount of variation of this organ, which, unless 
intermediate forms occurred, would certainly rank them 
as different species. Thus only one loose turn of the 
spiral may be present, and the form of the apex may vary 
considerably from that seen in fig. 9. This fact appears 
to be correlated in some way with the wide geographical 
distribution of the species, which ranges from the west 
coast of Greenland to the Mediterranean and Black Sea. 
This species has occurred at Skye, Millport, and Ply- 
mouth. At Port Erin it occurs in tide-pools. 
7. Promesostoma ovoideum, Schm. (Pl. XII figs. 10, 12.) 
A pale specimen of this species (wanting the usual black 
reticular pigment) occurred among shell-debris dredged 
outside Port Erin Breakwater, October, 1892, and is new to 
the British fauna. After leaving Port Erin I found it 
under similar conditions at Plymouth. 
8. Promesostoma lenticulatum,Schm. (PI. XII,figs.11,13.) 
This species, hitherto only seen by Schmidt who found 
it at the Faroe Islands, occurred among Corallina ma tide- 
pool near the Port Erin Station. 
