62 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



and furnished with adhesive papillae posteriorly, tapers 

 gradually forwards from the hinder fourth of its length. 

 Eeticular 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 determiri- 

 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. (PI. 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 Ienticulatitm,Schni. (PI. XII, figs. 11, 13.) 

 This species, hitherto only seen by Schmidt who found 



it at the Faroe Islands, occurred among Corallina in a tide- 

 pool near the Port Erin Station. 



