KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 25. N:0 2. 15o 



The precise phylogenetic position of this genus is not easy to determine. In the 

 general structuré of the dorsal cup, tegmen and arms it can hardly be distinguished from 

 Cyathocrinus; and m mere difference in the number of infrabasals, variable as it is, would 

 hardly be enough to warrärit its separation from that genus. At the same tiine it does 

 not seem probable that this genus is actually derived from Cyathocrinus: the axial ridg- 

 ing of the cup and the length, compression and folding of the ventral sac are not to be 

 found in that genus, but have closer parallels among the Dendrocrinites. Especially does 

 the little-known genus Palceocrinus present some striking resemblances. It seems pro- 

 bable then that Cyathocrinus and Gissocrinus are two parallel outgrowths from some 

 Ordovician or Cambrian stock, which was either Palceocrinus itself or a form combining 

 certain characters of Palceocrinus with some of Dendrocrinus. 



Gissocrinus had undoubtedly its largest and most typical development in Europé, 

 and has indeed not been recorded as yet from any other province. Too much stress must 

 not, however, be laid on negative evidence: British species of Gissocrinus were till quite 

 recently ascribed to Cyathocrinus, and the same is not unlikely to be the case with some 

 American species. 



Species of the genus: In Angelins Ieonographia are the names of seven species 

 of Gissocrinus, viz., G. arthriticus, G. nudus, G. tubulatus, G. elegans, G. punctuosus, G. 

 umbilicatus and G. macrodactylus. Of these names G. elegans, G. umbilicatus and G. 

 macrodactylus refer to species that there is no difficulty in recognising; but the spe- 

 cies to which the other names were applied are in a dire state of confusion. The difficul- 

 ties hitherto met with in the interpretation of Angelin's species are quite insignificant 

 compared with those that appal the student of the present genus. In the first place, the 

 forms that are figured under the names G. arthriticus and G. punctuosus seem to have 

 been separated from one another quite by accident; the only principle discoverable from 

 the diagnoses is that of ribbed or granular ornament, a principle which, even if followed, 

 could be of no value. In the second place, none of these specimens belong to G. 

 arthriticus of Phillips at all. That would not matter if they all belonged to one 

 species, for we could still use the name G. punctuosus. But unfortunately they belong 

 to two species, and when we enquire to which of these species the name G. punc- 

 tuosus may be given we find that the diagnosis applies equally to either speoies, and 

 that the figures are compounded from specimens of both species. After some hesitation 

 and after discussion with Prof. Lindstköm, I have decided to dröp the name G. punctuosus 

 altogether; if anyone censures me for setting aside the laws of nomenclature I willingly 

 hand över to him the task of determining the type-specimens. Thirdlv, the names G. nudus 

 and G. tubulatus have been proposed for one and the same specimen, which has been figured 

 twice över; and after all the specimen turns out to be nothing more than a rathér worn 

 crown belonging to the same species as some specimens of G. arthriticus Ang. and G. punctuosus. 

 This startling assertion had better be proved at once. First, to show that the two species 

 are based on the same specimen. A comparison of the diagnoses brings out the fact that. 

 although that of G. tubulatus is much longer, yet it contains nothing that is not in the 

 diagnosis of G. nudus. There were found in the Riksmuseum two specimens labelled G. 



K. Sv. Vet Akad. Handl. Band -.'.">. N:o 2 --'O 



