78 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



carination. The IBr 2 (axillaries) are two-fifths as long as broad with a carination in the 

 proximal part, but otherwise smooth. The 11+ partly broken arms are about 30 

 mm. long. 



Professor Gisle'n said that this species is very similar to P. aranea, differing in the 

 more distinctly conical centrodorsal and above all by the carination of the distal 

 cirrus segments. 



The two chief diagnostic features given in the description are, first, the occurrence 

 of a transition segment in the cirri beyond which is a series of highly polished spine- 

 bearing segments; and, second, the shortness of P 2 as compared with PI. These features 

 indicate that these specimens belong to a species of Thalassometridae, not to a species 

 of Charitometridae. Taken in connection with other characters given, especially the 

 compression and carination of the outer portion of the arms, they place the specimens 

 in the genus Parametra, in which genus they show no features by which they may be 

 distinguished from P. orion, of which they are undoubtedly only small individuals. 



Professor Gislen gave no formal description of Monachometra mortenseni, contenting 

 himself with notes on 12 specimens from Mortensen's station 9, the station from 

 which came the type specimen of his Perissometra carinala. (1) The centrodorsal 

 is a thick disk 3 mm. in diameter with the free dorsal pole flattened and 2.5 mm. in 

 diameter. The cirri are arranged in an almost simple row and in 15 columns. The 

 cirri are XVI, 17-19, 12 or 13 mm. long. The third segment is about as long as broad 

 and the sixth or seventh are the longest, half again as long as the distal breadth; the 

 outer part of this segment is polished and like the following segments is provided with 

 a weak dorsal prominence in the distal part. The opposing spine is small but distinct 

 and unforked. The radials are concealed. The IBr! are six times as broad as long. 

 The IBr 2 (axillaries) are two-fifths as long as broad and like the IBrj have a weak 

 median longitudinal carination; the proximal and distal borders are slightly raised. 

 The 1 1 arms are 55 mm. long. The IIBr series are 2. The proximal parts of the arms, 

 though closely set, are not wall-sided. There is a very weak and indistinct carination 

 out to the distal parts of the arms. Syzygies occur between brachials 3+4 and 13+14 

 and distally at intervals of from 6 to 10 muscular articulations. PI is 5 mm. long with 

 11-13 segments. P 2 is 2.8 mm. long with 8 segments. P 6 is 2.3 mm. long with 7 

 segments. The distal pinnules are 5.2 mm. long with 14-15 segments. The disk is 4.3 

 mm. in diameter and is coarsely granular. The anal cone is short, 1.3 mm. high. 

 The color is banded yellow-brown, the dorsal pole of the centrodorsal darker. 



(2) The diameter of the centrodorsal is 3 mm. The cirri are XV, 18-20, from 

 10-13 mm. long. The arms are 13 + , 55 mm. long. They are partly broken and 

 probably were 16 when the specimen was complete; four rays have 3, 3, 3, and 4 arms. 

 The median carination is indistinct. P t is 5 mm. long with 13 segments. P 2 is 3.7 mm. 

 long with 9 segments. P 3 is 2.8 mm. long with 7 segments. P 6 is 2.5 mm. long with 

 7 segments. The distal pinnules are 4.5 mm. long with 11 segments. 



(3) The diameter of the centrodorsal is 2.8 mm. The cirri are only XIII, 18, 

 about 11 mm. long. The arms are 11, 75 mm. long; the IBrj is eight times as broad 

 as long. The proximal portions of the arms are 1.2 mm. in breadth. PI is 6.2 mm. 

 long with 16 segments. P 3 is 3.2 mm. long with 8 segments. 



(4) The diameter of the centrodorsal is 3.5 mm. The cirri are XV, 21-23, from 

 13 to 18 mm. long in 14 columns. The 12 arms (perhaps 13 when the specimen was 



