KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 25. N:0 2. 21 



(c) With anal resting between r. post. R" and 1. post. R. 



Herpetocrinus. 



(d) With anal supported 011 whole of r. post. R s and often by r. ant. R s as weJl. 



Castocrinus, Eiichiroerinus, Calceocrinus, Halysiocrinus. 

 II. With 1. post. R and ant. R larger than the other RR, and with an anal supported by 

 upper angle of r. post. R. 



(a) With R. 



Pisocrinus, Triacrinus, Catycanthocrinus. 



(b) Without R'. 



Myocrinus, Catillocrinus. 

 III. With all RR fairly equal. 



(a) With moditication in r. post. R. 



(i) With simple unbranched arms. 



Hoplocrinus, Hybocrinus, Baerocriu us. 

 (n) With dichotomous arms. 



locrinus. 



(b) Without modification in r. post. R. 



(i) With slight disturbance of syinmetry due to anal in post. IR. 



Symbathocrinus, Storting ocrinus, Phimocrinus (?); Gasterocoma (?) , Nano- 

 crinus (?); Belemnocrinus. 

 (ii) Without disturbance of symmetry in anal IR. 



Stylocrinus; Cupressocrinus, Myrtillocrinus; Lageniocrinus (?); Allagecrinus. 



Such an arrangement may suggest relationships, but it does not represent thein, and 

 is therefore not the classification we are in search of. Before these genera c an be satis- 

 factorily arranged into fainilies we must have some idea as to their phylogeny. The 

 investigation of this would be so long a task and would lead us so very far awa\- from 

 Gotland that it seems better to be dogmatic for the present. It is, inoreover, hardly 

 necessary for the purpose of this paper, for no-one at any råte will doubt the general 

 validity of the families Heterocrinida; and Calceocrinida3 as maintained in the follöwing 

 pages. The only other family of Monocyclica with which we are concerned is the Piso- 

 crinida% which I venture to denne as follows. 



PlSOCRINIDJE. 



Inadunata Monocyclica in which 1. post. R and ant. R are much larger than the other 

 RR, r. post. R is the only R transversely bisected, and R' with the two large RR constitute 

 the greater part of the Dorsal Cup. Arms unbranched and non-pinnulate. An anal tube 

 rests on the posterior RR or on their processes. 



The name Pisocrinid* was first used by Angelin (Iconographia p. 20, 1878); but 

 he gave no detinition, and referred to it no genera except Pisocrinus. Von Zittel in 1879 

 (Handb. d. Palaeont. I, p. 348) defined the family and referred to it Pisocrinus, Triacrinus 

 and Catillocrinus; that is to say his family potentially included all the genera in the above 



