SEA-FISHERTES LABORATORY. 211 



(4) P. pellucidum, Bergh ; pyrif orm ; girdle at right 

 angles to long axis; three antapical spines. 

 L. 0045— 0-068 mm. Rare. (Fig. 3, No. 4.) 

 Sub-genus II. — Euperidinium : Girdle nearer apex on 

 left side ; antapical horns often present. 



(1) P. depressum,, Bailey; girdle oblique to long 



axis; horns subequal, hollow. L. 0'152 — 0'2 

 mm. Commonest form in Irish Sea. (Fig- 3, 

 No. 5, A and B.) 



(2) P. divergens, Ehrenberg ; girdle at right angles 



to long axis; inner side of antapical horns with 

 protuberances. L. 008 — 0*084 mm. Rare. 

 (Fig. 3, No. 6.) 



(3) P. conicum, Gran ; girdle at right angles to long 



axis ; antapical horns short and without pro- 

 tuberances ; left border of longitudinal furrow 

 straight. L. 0*048— 0'06 mm. Rare. (Fig. 3, 

 No. 7.) 



NOCTILTJCA. 



The distribution of Noctiluca throughout the year, 

 in 1911, was unusual in two respects — (1) in its presence 

 in fair quantity during many months (ten), and (2) in 

 having no marked maximum in summer and autumn. It- 

 seems to have remained in Port Erin Bay over the winter, 

 and was caught during the early months of the year in 

 diminishing numbers — up to 1,200 per haul in January, 

 300 in February, and 100 in March. It is not recorded 

 in April and May, but re-appears in small numbers in 

 June, reaches 1,200 in the best haul in July, a few in 

 August, and 1,800 in September, 2,000 (the top figure) in 

 October, fewer in November, and 1,600 in December. 



Hauls of between one and two thousand occur at 

 such diverse times of year as January, July, September, 

 October and December. 



