6o The American Geologist. July, i9oo 
The Devonian '''Lamprey \ Paleospondylus Gunni, Traquair. By 
Bashford Dean. 410, pp. 30, i pi. (N. Y. Acad. Sci., Memoir, Vol. 
II., pt. I, 1899.) 
Dr. Dean gives a full account of the history and affinities of this most 
interesting fish, once thought to be a "baby Coccosteus." A restoration 
at page 8 exhibits that author's view of the structure of this remarkable 
vertebrate. He separates it as a class from Pisces under a new division 
of Arthrognathi. 
In view of the great variation in size and form of the parts of this 
fossil, "Paleospondylus can hardly be looked upon as having attained 
its definite form. But if Paleospondylus be not the adult form, where, 
as Traquair asks, is the adult? Is it possible to believe with Dawson in 
its possible amphibian characters?'' It "cannot well be regarded as a 
larval form of either shark, lung-fish or Teleostome; it is far more likely 
to prove, as Huxley believed, a larval Arthrodire." G. F. M. 
Development of Agaricocrinus. By Mary Klem. (Trans. Acad. 
Sci. St. Louis, vol. X, No. 7, pp. 167-184, 4 pis., 1900). 
One of the beneficial results of getting the literature, species, and ge- 
ological range of a great zoological group in orderly arrangement is the 
impetus it gives the subsequent study. No better illustration exists than 
that of North American Paleozoic Crinoidea as reviewed by Wachsmuth 
and Springer, 
The little monograph on Agaricocrinus which has just appeared in- 
dicates how well large suites of limited groups may be treated to ad- 
vantage, and how special studies within a prescribed field may be made 
to yield results that are lasting. 
The author has given special attention to the ventral side of Agarico- 
crinus and its variation in a large series of a single species of which 
more than two dozen views are given. An attempt is made to find more 
satisfactory features than have been utilized heretofore for separating 
species. The conclusions reached are that "the best characters for 
specific separation are {a) the general aspect of the plates, {b) the ex- 
ternal ornamentation of the plates, and {c) the anal area. The geolo- 
eical formation is also of value, as we may assume with perfect safety 
that fossils found in the Chouteau group belong to different species from 
those found in the Burlington or Keokuk." 
The inquiry instituted by the author would point to the reduction of 
the forty-two species of American Agaricocrinus to ten. A considerable 
part of the monograph is devoted to criticising the late S, A. Miller's in- 
ordinate propensity to unnecessarily multiply species. After examining 
the synonymic lists, the question naturally arises, whether the pendulum 
has not swung too far the other way. Structural features that are almost 
generic in character are overlooked entirely and forms undoubtedly 
distinct thrown together under a single specific title. One must also 
question the last statement in the paragraph here quoted. It would be 
certainly very unsafe to assume that all forms from the Chouteau, Bur- 
lington and Keokuk limestones are necessarily specifically distinct. 
C. R. K. 
