122 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 8 



scription. So far, no species which resembles Thyone briareus is known 

 from the Pacific coasts of America except A. glasselli. 



To solve the question it is necessary to re-examine Troschel's material 

 in Berlin and possibly Lesson's type, if still extant. Very likely Lesson de- 

 scribed Pattalus mollis, the only large purplish form, and overlooked 

 some of the tentacles, while Troschel had either mislabeled material of 

 Thyone briareus before him, an undescribed Thyone, or Athyone glas- 

 selli. 



Family IL PhyllophoHdae 



Diagnosis. — Dendrochirota with more than 10 tentacles, the number 

 ranging from 15 to 30. The tentacles either definitely of two sizes, large 

 in the external circle, small in the inner, and appearing almost simultane- 

 ously, or the sizes intergrade, the 2 circles being indistinctly set off from 

 each other, and the full number is reached comparatively late in life. 

 Feet restricted to the ambulacra, or scattered also in the interambulacra. 

 Calcareous ring simple, or with distinct posterior prolongations; stone 

 canal and Polian vesicle often in large numbers. 



Spicules of various kinds, mostly as tables, often reduced with age. 

 Feet with end plate; walls with or without supporting tables or rods. 

 Introvert with tables or plates, tentacles with or without spicules. The 

 majority are shallow-water forms. 



Remarks. — A preliminary revision has been undertaken (Deichmann, 

 1938) which includes all the genera known from the American waters. 

 To this list is now added Athyonidium, established for the species for- 

 merly known as Thyone chilensis Semper. The latter is synonymous with 

 Eucyclus duplicatus, new genus, new species, established by Lampert, 

 1885, pp. 290-292. Lampert was fully aware of the close similarity to 

 Semper's species Thyone chilensis from Chile. Theel discussed the ques- 

 tion; he believed the two species were identical but concluded that the 

 number of tentacles possibly was more variable in the pohxhirote forms 

 than generally known. Ludwig concurred in Theel's opinion and assumed 

 that the tentacles were merely overlooked by Semper. He rejected, how- 

 ever, the genus Eucyclus as superfluous and united it with Thyonidiurn 

 under Phyllophorus. The Velero III has procured ample material of a 

 form which unquestionably refers to the species which Semper examined. 

 As in the case of Thyone ovulum Selenka — now Euthyonidium — in which 

 Selenka overlooked the inner circle of smaller tentacles, so here the inner 



