Reviews — 8iluriaa Crinoids of Chicago. 377 



Coccocrininje] 1 n.sp., Marsipocrinus 1 n.sp. ; Camerata, Melocrinus 

 or Mariacrinus (the evidence of the fixed brachials suggests the 

 former genus to Dr. Weller, but to me the latter) 1 sp., 

 Macro shjlocrinus 4 spp. of which two are new, Corymhocrinus 

 (i.e. Clonocrinus) 2 n.spp., Eiicalyptocrinus 13 spp. of which three 

 are new, Callicrinns 9 spp. of which four are new, the allied 

 Chicagocrinus n.g. with 2 n.spp., Periechocrinus 7 spp. of which 

 one is new ; Dicyclica, Inadunata, Ampheristocrinns 1 n.sp., 

 Cyathocrinus 3 spp. of which one is new, Crotalocrinus 1 n.sp., 

 Botryocrinus 1 sp. ; Flexibilia, Pycnosaccus 1 n.sp., Lecanocrimis 



2 spp., Ichthyocrinus 1 sp., and the doubtful Gazacrinus 2 n.spp. ; 

 Camerata, Thysanocrimis (i.e. Dimerocrinns) 4 spp., Cypliocrinus 

 1 n.sp., Lnmpterocrimis 4 spp. of which three are new, Siphonocrinus 



3 spp., Archceocnmis 1 n.sp., Lyriocrinus 1 sp. Thus this region 

 " contains, next to the Island of Gotland ... a larger number 

 of species of crinoids of this horizon than any similar region in the 

 world, so far as is known at the present time." Dr. Weller credits 

 Gotland with 172 species ; but, as he rightly says, " these are not all 

 associated in the same stratum." There are probably more than 69 

 species in bed / of Gotland, but fewer in bed d, which latter alone 

 corresponds to the Niagaran. Failure to recognize this vitiates the 

 contrast of " only six species of inadunate crinoids in the Chicago 

 fauna against 40 in Gotland," for bed d has yielded only two 

 Inadunate species, whereas I, with the classification given above, 

 find nine in the Chicago fauna. In this connection it is interesting 

 to note that bed d in Gotland is characterized by abundant Eucalypto- 

 crinidae, Dimerocrinidee, and Periechocrinida^, and that these are 

 the families most largely represented in the Chicago area. The 

 really interesting point, however, is that the crinoid fauna of this 

 ai"ea, and indeed the Silurian fauna of the Mississippi valley 

 generally, is related to the contemporaneous fauna of north-western 

 Europe more closely than to the neighbouring New York fauna. 

 The present memoir describes species of Crotalocrinus, Pycnosaccus, 

 and Corymhocrinus (i.e. Clonocrinus), genera hitherto known only 

 from England and Scandinavia, if we except a few Crotalocrinus 

 stems from Arctic America. Dr. Weller, from the consideration of 

 this and other evidence, concludes that the connection was by way 

 of a " North Polar sea with a great tongue stretching southward 

 through Hudson Bay to about latitude 33°. ... At the latitude 

 of New York there was a bay reaching to the eastward, in which 

 the Silurian sediments of the New York system were deposited." 

 Labrador, Greenland, and Scandinavia formed a more or less 

 continuous land mass, around which another tongue of the northern 

 sea extended south into Europe. In this connection Dr. Weller 

 raises an imaginary difficulty by saying that " in western Kussia the 

 Silurian strata are not exposed " ; tliey are indeed not so fully 

 developed as the Cambrian and Ordovician, but they do occur, and 

 are also found on the mainland of Sweden and Norway and in 

 Belgium, countries in which Dr. Weller's map does not indicate 

 them. These corrections ot course do but strengthen Dr. Weller's 



