126 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 8 



but was at that time unaware that ovulum was not a true Thyone. It 

 would, however, be a hitherto unknown phenomenon that the smaller 

 tentacles in the inner circle of a phyllophorid should be able to catch up 

 in size with the large ones, and for that reason alone it would seem 

 unlikely that ovulum could grow into Pattalus mollis usually with about 

 20 tentacles of almost identical size. Furthermore, the latter shows great 

 variation in the number of tentacles, while ovulum invariably seems to 

 acquire the full number at an early age. 



2. Euthyonidium veleronis, new species 

 Plate 24, Figs. 8-11 



Diagnosis. — Medium-sized form, up to 10 cm. long; body tapering 

 toward both ends with numerous soft feet scattered over the interambu- 

 lacra; toward the oral and anal ends arranged in a more orderly manner 

 along the ambulacra. Tentacles 5 large external pairs, and 5 inner smaller 

 pairs closely appressed.^ Calcareous ring with 5, almost rectangular radi- 

 als; posteriorly with short projections; interradials more or less heart 

 shaped, with the point forward directed, and overlapping the radials. 

 Stone canal single, attached in the dorsal mesentery ; Polian vesicles usu- 

 ally 3 in number, muscle stomach delicate; intestine with normal course; 

 retractors attached near the middle of the body where the 2 tufts of 

 gonads are also attached. 



Spicules a scattered layer of small tables with oval to squarish disk 

 with about 8 holes and dentate edge; spire low, mostly with 2 pillars, 

 often reduced to knobs. Feet with large end plate and occasionally a few 

 supporting rods. Introvert with tables ; tentacles with rosettes and small 

 curved rods, mostly with perforated ends. Color mottled grayish. 



Type. — Holotype, AHF no. 35. 



Type locality. — Station 465-35, Playa Blanca, Costa Rica, shale 

 beach between sand beach and rock reef, shore, February 8, 1935, 1 speci- 

 men. 



Distribution. — The type locality. 



Depth. — Shore. 



Specimens examined. — The type. 



Remarks. — The species is closely related to E. occidentalis (Ludwig) 

 known from the West Indies. 



8 As only the type was available, the tentacles in the inner circle were not dis- 

 sected out, but very likely this species has only 5 tentacles, deeply cleft, in the inner 

 circle. 



