10 TH. MORTENSEN, (Schwed. Südpolar-Exp. 



If it is correct, what seems to be indicated by the retension of the central pore, 

 that the stalk is retained for a considerably longer period than in other Crinoids, this 

 will point towards the fossil Tliiolliericrinus; in this form also the basalia are similar 

 to those of Xotocriiius, and likewise the centrodorsal is somewhat similar. 



The diagnosis of the new family must be as follows: 



Fam. Notocrinidae n. fam. 



Cirri robust, short jointed: cirrus sockets in lo vertical columns. Centrodorsal 

 with deep radial pits and large basal groove. Basalia present. Perisomatic plates 

 well developed, thick; the anal plate is retained. Pinnules robust, with short, cylin- 

 drical joints. Genital organs situated in the arms, not in the free part of the pinnules. 



Only genus known: Kotocrimis Mrt.SN. 



Ten arms. Cirri XXX — XL, with 40 — 60 joints. Brachials quite smooth. Pi 

 and P2 about equally long, with 15 short joints. Side and cover plates strongly de- 

 veloped on the ambulacra. Viviparous. 



Fam. Antedonidae A. H. Clark. 

 2. Isometra vivipara Mrtsn. 



PI. I, Figs. 6—10: PI. 11, Figs. 5 — 7. 



Antedon hirsiita P. H. C.\rp. K. A. Andersson: Brutpflege bei Antedon hirsuta Carpenter. 



Wissensch. Ergebnisse d. Schwed. Siidpolar-Exp. 1901 — 1903. Bd. V. 



1904, p. I — 7. Taf. I — II. 

 Isometra sp. A. H. Cl.^rk: Die Crinoiden der Antarktis. Deutsche Südpolar-Exp. XVI. 



Zoologie Bd. VIII. 1915, p- 106, 146. 

 Isometra vivipara. Th. Mortensen: Notocrinus virilis n. g., n. sp., a new viviparous Crinoid 



from the Antarctic Sea. Preliminary Notice. Vid. Medd. Dansk Naturh. 



Foren. Bd. 68. 1917, p- 208. 



Centrodorsal low, wider than long, rounded-conical; the dorsal pole smooth, 

 rounded, without cirrus sockets; the ventral edge somewhat irregularly sinuate, with 

 prominent interradial corners. Cirrus sockets rather closeset, irregularly arranged or, 

 partly, forming irregular rows (Pig. 6). 



Cirri ca. XXV — XXX, 28 — 35 (Fig. 7). The joints are short, those from ca. the 

 4th to the lOth somewhat longer than the rest. Beyond the middle of the cirrus 

 there is a fairly prominent, rounded, dorsal spine-; on the distal joints it is nearly 

 obsolete. Opposing spine erect; terminal claw short. The upper, longer cirri are 

 turned upwards, protruding over the disk between the arms (,P1. I, Fig. 10). 



Radiais low, the corners not produced. Costals nearly rectangular, more than 



