PART 5 A MONOGRAPH OF THE EXISTING CRINOIDS 549 



ably one distal segment lost, it is estimated to have had about 1 1 segments when com- 

 plete and been over 4 mm. long. The segments bej'ond the third are elongated, up to 

 six times as long as broad, with flared and spinous distal ends. The gonad, an ovary, 

 lies along the third to fifth and part of the sixth segments. A detached distal genital 

 pinnule, with an ambulacral fuiTow, was, when complete, of 11 segments and 

 about 5 mm. long. The segments are elongated as in P3. 



There is then a far greater difference in length between the oral and genital pin- 

 nules of this specimen than in those of the type, due to the greater elongation of the 

 segments of the genital pinnules in this specimen. 



Pi and P2 of the other specimen are shorter, with sLx segments and about 2 mm. 

 long. P3 is the first genital pinnule. The specimen is a male. 



The pinnule ambulacra are lined by reduced rodlike side plates, two or three to 

 each segment. The rods may be smooth, or one or both ends may be knobbed, branched 

 or expanded into small reticulated plates. At the ends of some of the side plates are 

 much shorter rods, usually studded with spikes, which are cover plates. There are no 

 spicules in the tentacles. The side and cover plates are similar to, but better developed, 

 than those of the type. 



The female specimen shows that this species too is viviparous. The brood pouches 

 lie on the ventral side of the ovaries, not alongside them as in E. concinna; they may 

 be on the proximal or on the distal part of the ovary and they may overlap it at either 

 end. The eggs in the ovaries vary in size up to 0.3 mm. Three of the genital pinnules 

 examined, all of them proximal ones, were found to contain embrj'os in the brood pouch. 

 In one pouch there were three embryos, none with skeletal plates. The other two each 

 have two embryos which are irregular in shape and about 0.4 mm. long. None shows 

 any trace of ciliated bands. Skeletal plates are beginning to appear in some. A 

 terminal stem plate and a number of stem joints can be seen in one as well as some of the 

 plates of the calyx. The brood pouches have such thin walls that they may easily be 

 overlooked when collapsed. Judging from a number of pinnules in this condition, they 

 often lie partly proximal to the ovary, on the third segment of the pinnule and partly 

 on the ovary. 



In the male specimen, a large triangular ossicle separates one of the radials from 

 the centrodorsal and from one of the other radials. 



Dr. John sent me the type specimen of E. aurora so that I might compare it with 

 E. concinna. It is considerably larger than the latter, its centrodorsal is lower and 

 broader with more numerous cirrus sockets, which are more iiTegularly arranged. 

 Its longer cirri have more segments. The radials and axillaries are longer. The ele- 

 ments of the division series and brachials do not have their central portions abruptly 

 elevated and prominently spinous as in E. concinna. 



Dr. John was able to compare E. aurora directly with E. hirsuta. It is far less 

 spinous than hirsuta on the arms and the shapes of the elements of the division series 

 and first two brachials are quite different in the two species. The cirrus sockets of 

 E. hirsuta are in about 15 irregular columns. Dr. John says that E. aurora is easily 

 distinguished from E. fraseri by the smaller number of cirrus segments, and from 

 E. marri by the fact that its cirrus sockets are in columnar arrangement. Pi is not much 

 more massive than Pj, and the segments of the lower genital pinnules carrying the 

 gonads are not expanded. 



