THE HYDROID FAUNA OF THE WEST OF SCOTLAND 219 



Gonosome. The gonangia vary much in size, but their out- 

 line is fairly constant, except in such abnormal cases as are figured 

 below. They are elongate, ovate, with an insignificant stalk, a 

 round aperture, and a short collar surrounded by translucent points 

 of chitin. They arise immediately proximal to a hydrotheca and 

 occur in close rows, a single hydrotheca being sometimes accom- 

 panied by two gonangia (fig. 2). 



Fig. 2. 



Fig. 5- 



Fig. 3. Fig. 4. 



FIGS. 2-5. THUIARIA TENERA. x 30. 



Fig. 2. Fragment of branch from Tighnabruaich, with hydrotheca: and gonangia. 

 ,, 3. ,, ,, ,, Mull of Cantyre, with hydrothecoe. 



,, 4. Abnormal annularly constricted gonangia, Tighnabruaich. 



,, 5. Abnormal branch terminating in two gonangia. 



The following measurements give some idea of the variable pro- 

 portions of the species : 



Specimens from Specimens from 



Tighnabruaich. 



Hydrotheca, length free . 

 Hydrotheca, length adnate 

 Hydrotheca, greatest diameter . 

 Hydrotheca, diameter at mouth 



Cantyre. 



o.i 7-0.29 mm. 

 0.14-0.15 mm. 

 o.i 2-0.18 mm. 

 0.06 mm. 



o. 2 1-0.29 mm - 



0.25-0.28 mm. 



o. 14-0. i 7 mm. 



0.08-0.10 mm. 

 Gonangium, length . . . 0.81-1.33 mm - 

 Gonangium, greatest diameter . 0.31-0.44 mm. 



Localities. CLYDE SEA AREA. KYLES OF BUTE off Burnt 

 Islands ; off Tighnabruaich (specimens in Rothesay Museum 

 and in my collection). 



MULL OF CANTYRE, 50 fms., growing on Halerium muricatum; 

 small fragment. 



Although this species is not to be found in British lists, speci- 

 mens in the Natural History Museum, Vienna, have been recorded 



