I50 THE AMERICAN NATURALIST. [Vor. XXXIV. 
The volume is well printed by the Nature Publishing Company, and 
very well illustrated, in part with original photographs. 
This book can be highly commended for its honesty and directness 
of purpose. Its author stands on his own feet and neither poses 
nor gushes, and his work is worthy of its purpose. DS 
ZOOLOGY. 
Artificial Production of Rhythmic Muscle Contractions. — 
Professor Loeb’ has pointed out that certain solutions containing 
ions of sodium, chlorine, lithium, bromine, iodine, etc., may cause 
rhythmical contractions in muscle, and that solutions containing 
certain other ions, calcium, potassium, magnesium, barium, strontium, 
etc. check such contractions. It is supposed that the rhythmic 
contractions are the result of the combination of the particular ions 
with the muscle. The rhythmic action of the heart may be a natural 
example of this kind of action. G. H. P. 
Evermann and Marsh on Fishes of Puerto Rico. —In the 
Report of the United States Fish Commission for 1899, Dr. Barton W. 
Evermann and Willard C. Marsh give an account of new species 
discovered by them in the late cruise of the Zisk Hawk about the 
island of Puerto Rico under Dr. Evermann’s direction. An elabo- 
rate account of these important investigations is in preparation. The 
present paper gives a preliminary account of three new genera of 
Blenniidz — Gillias, allied to Tripterygion ; Auchenistius, a Blenny, 
allied to Auchenopterus; and Coralliozetus, allied to Ophioblennius 
— and of twenty new species belonging to different families. These 
are: Lycodontis jordani, Stolephorus gilberti, Stolephorus garmani, 
Prionodes baldwini, Calamus kendalli, Doratonotus decoris, Sicydium 
caguite, Gobius bayamonensis, Bollmannia boqueronensis, Microgobius 
meeki, Gillias jordani, Malacoctenus culebre, Malacoctenus moorei, Mal- 
acottenus puertoricensis, Auchenistius stahli, Auchenopterus albicaudus, 
Auchenopterus rubescens, Auchenopterus cingulatus, Auchenopterus 
fajardo, and Coralliozetus cardone. Most of these are small fishes of 
! Loeb, J. Ueber Ionen welche rhythmische Zuckungen der Skelettmuskeln 
hervorrufen, Festschrift zum 70. Geburtstage des Herrn Geheimrath Prof. Dr. A. 
fick, pp. 101-119. 
