Swedish Cambrian-Siberian H. and C. 439 
list of all described Cambrian and Silurian (Upper and Lower) 
species, with synonyms. The total number of species of Hyolithus, 
including those of the Devonian, Cambrian nnd Permian, are stated 
by Holm at178. He gives a list of species-names suppressed as 
being synonyms or wrongly applied; also an historical outline of 
the literature of the genus in Sweden, aise an “Attempt at a 
Natural Grouping.” 
' This scheme or table for a natural grouping, intended to: show 
the derivation and supposed genetic relations of the several sec- 
tions of Hyolithes will interest biologists. Dr. Holm finds that the 
only species outside of Scandinavia which can be used for a pur- 
pose of this kind are those of Bohemia and North America, others 
are few in number, or imperfectly described or based on defective 
material. The oldest forms known at.the base of the Cambrian 
show already |wo ‘stem forms,” viz., the two sub-genera of Hyo- 
lithes, which Dr. Holm recognises represented by several species ; 
hence he infers that tha Lower Cambrian Hyolithes of necessity 
must have sprung from some older, and to us unknown fauna. 
_ About sixty-three pages of the work are devoted to descriptions 
of the numerous Swedish s;ecies, most of which are herein for the 
first time described. 
CONULARIID As. 
The Conularias form a less important feature of this work than 
the Hyolithide, the species of the former genus being. somewhat 
scarce in Sweden, and the work not treating of any later species 
than those of Silurian aze. But the description of the group has 
been carried out with the same completeness and assiduous atten- 
tion to detail which marks the part relating to the Hyolithidee. 
Bohemia still stands forth as “ par excellence” the region of the 
Conularias, with twenty-four species, unearthed and described 
chiefly by the illustrious Barrande. Sweden presents sixteen 
species described chiefly by Holm and Lindstrém, while the 
United States has eighteen species, nearly half of which have been 
described by Jas. Hall. The only species known, older than the 
Lower Silurian, is one described by Walcott from the Upper Cam- 
brian. 
As with Hyolithes so in this genus Dr. Holm gives a tentative 
natural grouping of the species. He divides them as follows: 
1. Leves. Shell smooth, only having growth lines, which appear 
as wrinkles. Segmental line indented. 
2. Longitudinales. A preponderating sculpture of longitudinal 
elevated lines. Segmental line elevated. 
3. Monilifere. Sculpture obliterated by cross threads beset with 
