212 SMITHSONIAN INSTITUTION 



inally described as Cyathocrinus interbrachiatus by Angelin. When Wachsmuth and Springer 

 proposed the genus Gnorimocrinus to receive the Swedish Taxocrini two species were thus 

 brought together with the same name, so they renamed this one G. loveni. With its removal 

 to another genus in which there is no such clash of names Angelin's priority must be recog- 

 nized and the original name restored ; therefore the type of Meristocrinus is M. interbrach- 

 iatus, instead of M. loveni as formerly stated by me. 



Angelin's type specimen proves to be misshapen from injury and reparation during life 

 (PI. XVII, figs. ia-c), but another one since found furnishes the characters upon which the 

 genus is defined (figs. 2a-d). It will be seen from these figures that this genus is near the 

 border line between Taxocrinidae and the other families in about the same way as Synero- 

 crinus. The anal structure is that of a tube-like series ; but because it does not originate on the 

 posterior basal, from which it is separated by an anal plate suturally joined to the basal and 

 adjacent brachials, the genus must be held to belong in the present family upon the principles 

 already explained. The anal series is essentially similar to that of- Temnocrinus; but the 

 occurrence of so many different forms with an additional primibrach from several localities 

 indicates that the modification is probably more than a mere sporadic or specific variation. 

 In the typical form the genus may represent an intermediate step in the transition from 

 Temnocrinus to the Carboniferous Forbesiocrinus. 



The five species include forms from Gotland and England. They are a heterogeneous 

 lot and do not lend themselves to systematic analysis. 



Meristocrinus interbrachiatus (Angelin) 

 Plate XVII, figs. 1-3 



Cyathocrinus interbrachiatus Angelin, Icon. Crin. Suec, 1878, pi. 23, figs. 2, 20; pi. 29, fig. 78. 

 Gnorimocrinus loveni, Wachsmuth and Springer, Revision Palaeocrinoidea, pt. 1, 1879, p. 50. 

 Meristocrinus loveni, Springer, Jour. Geology, XIV, 1906, p. 515. 



Type of the genus. 



A rather large species. Crown elongate, height to width at LIBn, i to i. 

 Spread of calyx from base to IAx, i to 3. Rays deeply rounded, interbrachial 

 areas depressed. Base broad, tapering gradually to the expanded column. 

 Sutures straight. Surface smooth. Maximum crown, 35 mm. high by 22 wide; 

 base, 7 mm. 



IBB appearing as low pentagons above the column. BB large, but smaller 



than RR. RA smaller than R. Anal x large, followed by a vertical series not 



over half its width, adjoining right posterior ray and bordered by perisome at 



the left. iBr one or two small plates followed by perisome which extends to the 



second and third axil. RR the largest plates in the calyx. IBr 3, decidedly 



shorter than RR but nearly as wide. IIBr 4 to 6, with two or more bifurcations 



above. Column large, composed next to calyx of very thin ossicles, and slightly 



narrowing downward. 



The description is made chiefly from figures 2a-c of Plate XVII, but with corroboration 

 from the other specimens. The type is abnormal, and singularly enough another specimen 

 of this rare species characteristic in other respects is also abnormal in the anal side (PI. XVII, 



fig- -3k) ■ 



Types. Riks Museum, Stockholm. 



Horizon and locality. Silurian, Wenlock Group; Faro (horizon d) and Wisby (hori- 

 zon /), Gotland, Sweden. 



