Beaumont — Fauna and Flora of Valencia Harbour, Ireland. 821 



Tetrastemma candidum (0. P. Miiller). 



1^0 specimens exactly agreeing with Burger's T. candidum 

 have come under my observation. In particular I have never 

 seen one in whicli the cephalic furrows showed conspicuously 

 as brown streaks. It is very usual in this and allied foims to 

 find a concentration of the orange granules (frequently present 

 in the skin) along the cephalic gTOOves ; but the fact is not 

 obvious except under the microscope. ISTor have I observed 

 the cerebral organ to be particularly small. 



The many specimens of Tetrastemma lacking pigment bands 

 on the head, and coming under the broad heading T. candidum 

 (as usually defined) fall into thi'ee sets : — 



(A). The common form in the harbour both on the dredging 

 grounds (5-8 fms.) and between tide-marks. Earely exceed- 

 ing 10 mm. in length. Body slender. Head fiattened, spathu- 

 late in outline. Eyes medium in size, about equal, anterior 

 pair more widely separated than the posterior. Colour variable : 

 pale dull yellow, deep apricot yellow, green, dull brownish 

 orange ; due chiefly to gut, the outer tissues being pale fiesh- 

 coloux or yellowish. Gonads, when well developed, may give 

 a grey look to the general colour. In none was there a patch 

 of opaque white flakes (gland cells) present on the head, or a 

 line of opaque white along the middle of the dorsum. In a 

 few there were traces of brown pigment between the anterior 

 and posterior eyes on each side, or more rarely between and 

 somewhat posterior to the anterior eyes. 



Central stylet apparatus slender ; length of the stylet two- 

 thirds to three-quarters that of the handle, which is usually 

 moderately constricted in the middle, the posterior end more 

 swollen than the anterior, but the shape varies a good deal. 

 Generally two reserve stylets in each pouch. 



The greater number examined were males with well deve- 

 loped testes, but a few ripe females were also found. 



(B.) Not common, a few specimens dredged on shell-beds, 

 and in Port Magee Channel on JS^ullipore ground. All were 

 females. They were similar to the form described by myself 

 fi'om Port Erin (1895), and by Riches from Plymouth (1893). 

 Length, 20-30 mm. Body slender, less than 1 mm. wide 

 when well extended. Head very similar in shape to T. mel- 

 anocephalum (var. coronatum). Eyes like those in (A), medium 

 in size ; black and distinct. 



