270 NATURAL SCIENCE [October 
arm-skeleton ; our fossil, however, has an arm-skeleton consisting of 
a narrow loop, which projects forward into the shell cavity, and this 
places it in II. B.c. 2. The first sub-division of this is according to 
the length and curve of the loop, and our brachiopod agrees with the 
second paragraph, “Loop recurrent, long. 11.” Turning to 11, we 
read “The loop free,’ which does not agree with our specimen; and 
then, “The loop again fixed to the median septum of the small valve. 
16.” Reference to 16 again gives us two sub-divisions, the first of 
which includes shells that are “Smooth, . . . have large foramen, 
and rudimentary deltidium. 17.” Number 17 includes 3 genera, 
Kingena, Magas, and Rhynchora. Kingena has “ median septum in 
the large valve,” and a “cross-band connecting the recurrent loop- 
bands”; these structures are not found in our fossil. Rhynchora has 
“hinge-line straight, lone, large valve with area”; this also does not 
fit. We are therefore restricted to Magas, and find in fact that the 
specimen agrees with the characters here ascribed to that genus. 
Now this is admirable, and as scientific as it is possible for such keys 
to be. But how often will the student or the field-geologist have a 
specimen of Magas pumilus showing all, or even a few, of the necessary 
characters 2? Not one specimen in a hundred shows them. In fact 
Professor Koken himself says of the Brachiopoda: “Since the delicate 
calcareous bands are usually destroyed or only discoverable by 
laborious preparation, other characters have to be used in practice.” 
In short, give the student a decent work of reference, such as David- 
son’s Monograph or the “ Paléontologie Francaise,” and he will have 
determined genus and species long before you have made up your 
mind whether the specimen has a brachial skeleton at all. The 
truth is that the principles of classification are one thing and the 
methods of fossil-spotting are another. The first essential for the 
latter is an extensive acquaintance with specimens. Any collector 
of Chalk fossils can tell Magas pumulus if he has once seen it. When 
he has this acquaintance, then he can proceed to the true knowledge 
required for the best systematic work. We must learn these concrete 
sciences like we learn a language: get a good vocabulary first, and 
proceed to the structure and syntax afterwards. 
The second section of the book gives short diagnoses of the chief 
species characteristic of the various formations, and is to be used after 
one has determined the genus. Itis inevitably incomplete, and chiefly 
intended for German students. Even for the fossils of Germany it is 
not to be relied on without confirmation by the more complete original 
monographs ; and this being so, it is a pity that there are no references 
to literature. The fortunate collector of a Zaxocrinus rhenanus cer- 
tainly should not be able to identify it as a Cyathocrinus, the genus in 
which Dr Koken leaves it. Some of the genera and species to which 
reference is made, especially among the Gastropoda, we have been 
unable to discover in literature at all, and have a strong suspicion 
that they are here introduced for the first time (¢.g., Hctomaria, p. 395). 
This is undoubtedly the case with the name Amorphocystites, intro- 
duced in a footnote (p. 411) as proposed by Jaekel for Caryocystis 
testudinarius Von Buch and C. pumilus Eichwald. It is very doubt- 
ful if any such change of nomenclature be needed ; and in any case this 
hole-and-corner method of bringing out new names has never yet been 
