PAKT 5 A MONOGRAPH OP THE EXISTING CRINOIDS 779 



sockets. The proportions of the cirrus segments are the same as shown in Carpenter's 

 figure. The size is similar to that of the specimen figured by Carpenter (pi. 69, fig. 5). 

 The arms measure 20 mm. to the distal end of the nineteenth brachial. The distal 

 intersyzygial interval is usually 3 muscular articulations. On the disk 5 ambulacra! 

 grooves leave the mouth, dividing about midway to the arm bases; one of these grooves, 

 the right posterior, divides into 3, while one, the left anterior, is undivided. 



The example dredged by the Gauss in 2425 meters resembles the preceding. The 

 cirri are XIV. The longest cirrus stump measures 16 mm. to the distal end of the 

 eighth segment. The first segment is about twice as broad as long, the second is about 

 as long as the median width with a strong central constriction, the third is 1.7 mm. in 

 length, and the fourth is 2.8 mm. long; the following gradually decrease in length, the 

 eighth being 2.2 mm. long. The cirri are very slender, resembling the cirri of such 

 species of Pentametrocrinus as P. semveri or P. variant. 



Young. The ccutrodorsal of the juvenile type specimen of T. renovatus is small, 

 flattened hemispherical, with the central canal completely closed so that it must have 

 been for some little time detached from the larval column. 



The bases of about VI cirri are attached to the ceutrodorsal, and there are pits for 

 the reception of 2 or 3 more. In the largest stump which is preserved the first 2 seg- 

 ments are short, but the third reaches a length of 1.5 mm. so that, as remarked by 

 Carpenter, the cirri must have been very like those of the species of Pentametrocrinus, 

 which have a succession of very long segments following the short basal ones. 



The basals are almost trapezoidal, much broader below than above, and in contact 

 with one another by their truncated lower lateral angles. The middle of the lower 

 edge of each is slightly tubercular. 



On the narrow upper or distal edge of the basals rest the interradials, which are oblong 

 and a little higher than broad. Four of these terminate in a free edge at the margin 

 of the disk, where they are in contact with the lowest of the perisomic plates. But 

 that in the posterior interradius bears a rudimentary arm of 4 or 5 segments, the last 

 of which ends freely. 



The radials are much larger than the interradials, and are rather strongly convex 

 dorsally. They are united to the first brachials as usual by a muscular articulation. 



The brachials are long, slender, and cylindrical; there appears to be a synarthry 

 between the first and second. 



One of the 5 arms seems to be broken off at a syzygy between brachials 6 + 7, while 

 in another there are syzygies between brachials 4 + 5 and 9 + 10. 



The first pinnule is on the second brachial, on the right side on 3 arms and on the 

 left in the other 2. The pinnules are very delicate, and are composed of long and 

 slender segments. 



The central portion of the disk is occupied by 5 relatively large orals which stand 

 up around the peristome. Between these and the margin are 2 or 3 irregular rows of 

 small perisomic plates, some of them extending up onto the lower portion of the long 

 anal tube. 



There are no plates along the bracbial ambulacra, which lie in the arm grooves 

 close down between the muscles. 



There are no traces of sacculi. 



The present whereabouts of this specimen are unknown. 



