302 BULLETIN 82, UNITED STATES NATIONAL MUSEUM VOLUME 1 



With the first pair of brachials repeated: A specimen from ofif San Diego, Cali- 

 fornia, in 183 meters collected by Pi of. William E. Ritter is peculiar in having an ad- 

 ditional first and second brachial inserted between a IBr axillary and the normal first 

 brachial of its left derivative (vol. 1, part 2, fig. 131, p. 79; U.S.N.M., 36299). This 

 interpolated pair of brachials is further interesting in being of the kind normal to a 

 right derivative from a IBr axillary though it occurs on a left, and the outer element 

 of the pair bears a pinnule on its inner side. The next two brachials are normal first 

 and second brachials of a left arm with the characters of the two preceding just 

 reversed. 



With 11 arms: A specunen from Albatross station 3051 (U.S.N. M., 36042) has 11 

 arms, one IIBr 2 series being developed on the left side of a IBr axillary. On the 

 left (outer) derivative from the IIBr axillary the first syzygy is between brachials 

 4 + 5; on the right (inner) derivative it is between brachials 1 + 2. 



Pentacrinoid young. — Dr. Th. Mortensen has described in detail the pentacrinoids 

 of this species. 



In the youngest stage studied by him the oral valves have opened and the primary 

 tentacles are beginning to protrude. The calyx consists only of the basals and orals. 

 The basals are peculiar in having a rather broad unfenestrated lateral border. The 

 orals are deeply depressed along the median line, the sides being bent gracefully out- 

 wards. There are no infrabasals. Dr. Mortensen sa3's that while the radials are not 

 yet formed the IBri (axillary) has already appeared, lying as a small fenestrated plate 

 about midway on the primary tentacle beyond the first sacculus, which is also distinct. 

 In another specunen of the same stage the axillary was only a small spicule not yet fene- 

 strated. He remarks that, so far as he knows, this is the first case recorded where the 

 axillary appears before the radials. That this plate is really the axillary is shown 

 beyond doubt, he says, by a slightly older stage in which the radial plate has been 

 formed and there is, below the first formed plate in the tentacle, a small plate that can 

 only represent the IBrj. The radianal is large and rounded, encroaching upon the 

 adjoining basals. It is the first plate to appear after the basals and orals, the order of 

 appearance of the various plates being, according to Mortensen, (1) the basals and orals, 

 (2) the radianal, (3) the IBrj, (4) the radials, and (5) the IBr,. 



In this slightly older specimen the IBri had appeared only in one radius, that to 

 the left of the anal radius; "the radial plate was also found to diminish in size the same 

 way round, and partly also the axillary, which latter was, however, found to be largest 

 in the anal radius." 



In this example the column consists of 16 segments, the 4 topmost being quite short, 

 the central long and cylindrical, and the 3 lowest quite short; the terminal stem plate 

 is irregularly lobed. 



In another specimen the radials have just been formed while the IBri has not as 

 yet appeared. Some meshwork is beginning to develop on the orals, and a growth zone 

 can be observed in the lower part of the orals and the upper part of the basals. Because 

 of the large size of the radianal the adjoining radial lies to the right of the median line; 

 resorption of the lower edge of the oral has begun. 



In a shghtly older specimen one of the basals was abnormal, smaller and shorter 

 than the others and reaching only halfway down so as not to meet the upper end of 

 the stalk. There are 19 columnals, the central ones being very elongate and slender. 



