118 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 8 



264-34. Petatlan Bay, Mex., 25 fms., March 2, 1934, 1 specimen. 

 683-37. Outside of Concepcion Bay, Max., March 15, 1937, 30 speci- 

 mens. 

 744-37. Near Point Piaxtia, Sinaloa, Mex., Gulf of Calif., April 1, 

 1937, 7 specimens. 



Remarks. — The species resembles lugubris to an extraordinary degree, 

 and future workers may decide that it merely represents a variety of that 

 form. It is easily distinguished by the more simple supporting tables in the 

 ventral feet, the shorter buttons which seem to lack all tendency to become 

 lozenge shaped with accessory holes in the ends, and in the larger tables 

 in the introvert and the absence of heavier rods and plates in the stem of 

 the tentacles. The larger size and the darker color are, of course, quite 

 useless characters, as lugubris possibly may be discovered to reach the 

 same size and, although a dark color is common, paler individuals have 

 been found. In no case have embryos been discovered, so presumably this 

 species is not viviparous as are lugubris and rubra. 



The species has in some localities been found with the larger and 

 paler Neothyone gibbosa, and the possibility has been considered that the 

 latter represents senescent specimens of pseudolugubris, in which the ex- 

 ternal layer of reticulated plates has been lost. The spicules seem, how- 

 ever, to be definitely different. Pachythyone pseudolugubris shows little 

 tendency to form handles, and the buttons have rarely more than 2 central 

 knobs (except in the lozenge-shaped buttons), while Neothyone gibbosa 

 normally forms handles, and as often as not the external handle has 3 

 knobs. Also the latter species shows definitely a tendency to develop large, 

 smooth supporting plates in the ventral feet, while such plates are almost 

 unknown in Pachythyone pseudolugubris, where the few supporting plates 

 which lack a spire are narrow, thick, and in most cases knobbed. 



Genus 11. ATHYONE, new genus 



Diagnosis. — Medium-sized to large forms. Feet numerous, fairly 

 stout. Tentacles large, bushy, the 2 ventral smaller. Skin soft, with few 

 spicules. Calcareous ring stout with broad radials with distinct posterior 

 prolongations and tall interradials with short anterior tooth. 



Spicules scattered swollen 4-holed buttons, often incomplete. Feet 

 with loose-meshed end plate and numerous supporting rods, undoubtedly 

 derived from tables. Introvert and tentacles with rosettes. 



Type species. — Athyone glasselli (Deichmann). 



