ANTARCTIC BRYOZOA — ROGICK 225 



with B. discreta, and their erection was based on characters which vary 

 so much that it is my sincere opinion that B. robusta, B. intermedia, 

 and B. antarctica are synonyms of D. discreta. Barentsia, as an in- 

 tensive stud}^ of many Hving colonies of B. laxa showed (Rogick, 1948), 

 can vary tremendously in length. Johnston and Angel's studies of 

 B. antarctica were of necessity based on 14 stalks and 4 admittedly 

 immature calyces, the former a very variable feature as to length 

 and the latter not developed far enough (might even have been re- 

 generating heads) to be of great value in determining final tentacle 

 number. 



Barentsia discreta consists of upright, stalked, calyx-topped, yel- 

 lowish zoids that are connected basally with others by narrow stolons. 



In side view the calyx is broadly oval, with the anterior surface 

 shorter and more curved than the posterior surface (pi. 1, A, D). The 

 tentacle number extremes vary from 12 (Jullien) to 29 (Harmer), 

 depending upon the age and size of calyx. In the U. S. Navy's 

 specimens the tentacles were badly tangled or contracted, but one 

 calyx had 17 tentacles. On another calyx 14 tentacles were counted 

 on one side but it was impossible to tell how many were on the opposite 

 side. Calyx dimensions as well as other measurements are given in 

 table 1. The calyx is deciduous and breaks off easily, but stalks may 

 regenerate new ones, thus accounting for unusually small heads with 

 a small number of tentacles on very long stalks, as in Johnston and 

 Angel's B. antarctica. 



Barentsia discreta is recognized by the peculiarity of its stalk. The 

 stalk consists of two parts — the shorter, thick, basal musclium and the 

 much longer, slender, pedicel-peduncle. The musclium (pi. 1,A,B) 

 is a flexible, barrellike, muscular cylinder found in varying degrees of 

 contraction (wrinkling or smoothness). It is topped by a thin, hard, 

 chitinous, conical cap from which the long, slender, characteristically 

 marked shaft continues (pi. 1,E). The shaft consists of the long rigid 

 proximal peduncle and the short flexible distal pedicel, the two merging 

 almost imperceptibly into each other. An incomplete septum sepa- 

 rates the narrow peduncle from the flared cap covering the musclium. 

 The peduncle wall has a thin outer and thicker inner cuticle (Ehlers, 

 1890, pi. 2, fig. 22). Small cone-shaped pits occur in scattered and 

 irregular manner in the inner cuticle layer (pi. 1,E) and are the key 

 character for this species. The pedicel is soft, contractile, thinner- 

 walled, and lacks the pores or pits. 



Two to five stolons lead outward from below the musclium base, 

 the majority of them at right angles to each other (pi. 1,B). The 

 stolons are separated from the musclium by incomplete septa and are 

 of variable length. 



