IIYDROIDA II 



IO3 



either side in the broad plane of the colony. The hydrotheca has a free adcauline distal wall part, 

 half as long as the hydrotheca or somewhat less, about i'/j times the opening diameter. The hydro- 

 theca has its greatest breadth at the middle, and narrows down both towards the base and towards 

 the opening, which is set perpendicular to the axis of the hydrotheca. The free portion of the adcau- 

 line wall is as a rule furnished with somewhat faintly marked transverse furrows. The opening margin 

 has four low teeth and four triangular lid plates in the sinuses between them. 



The gonothecse proceed from the branches close under the base of the hydrothecse. They are 

 oval, more or less furrowed transversely in the distal half, and have distally a narrow central opening 

 with two diametrically opposite short broad teeth. 



200 m. _, 600m. ._ 1000m. 2ooom. 



Fig. LV. The distribution of Sertularella Gayi in the Northern Atlantic. 

 In the hatched regions a common although scattered occurrence is stated in the literature without precise data. 



Material : 



depth 132 fathoms 7,2° 



3 l6 5'9 

 170 



204 4,1° 



"Ingolf" St. 1 62°3o' N., 8°2i' W., 



- 55 63*33' N, 15W W, 



- 85 63°2i' N., 25°2i' W., 



- 94 6 4 ° 5 6' N, 3 6°i 9 ' W, 



- 98 65°38' N., 26°27' W., 

 "Thor" 6 4 °o6' N., 23°i4' W., 

 Iceland: Ingolfshofdi g l / 2 miles in N. by E. 1 _,E., depth 53 fathoms. 

 The Faroe Islands: 6o°23' N -> 8 r 55' W., 225 



138 5,9° 



98 metres [labelled Sertularella polyzonias] 



