Some remarks on Dr. Thilo’s memoir on 
» Die Umbildungen an den Gliedmafsen der Fische«. 
By 
William Sorensen 
(Kjöbenhavn). 
With 6 figures in text. 
In the preceding volume of this Jahrbuch Dr. O. TuıLo has 
published the above-mentioned interesting memoir, which has been 
elaborated with great diligence, as may be seen from his having 
already published the preliminary studies! on the said subjeet in 1879. 
In the greater part of his present memoir he is occupied with the 
mechanisms found at the spinous rays of several fishes which serve 
for fixing the spines. As, in his text, Dr. Tuo refers to the 
statements of other authors only with regard to two genera (Acan- 
thurus, pag. 324, and Monocentris, pag. 339), one might easily be 
led to suppose that most of these mechanisms had not been treated 
before. In this case the impression would hardly be correct since — 
not to mention other authors — I have several years ago treated 
the said apparatus in nearly the same genera, though it is true I 
had not examined Chorinemus, Amphacanthus, Naseus, Monocentris, 
and Arius, while on the other hand I had given an account of the 
relations in Balistes, Capros, Cottus, and the following genera of 
Siluroids: Doras, Euanemus, Pseudaroides, Platystoma, and Pleco- 
stomus. According to the wish expressed by Dr. Tuo, I had the 
1 0. Tuto, Die Sperrgelenke an den Stacheln einiger Welse, des Stich- 
linges und des Einhornes. Inaugural-Dissertation. Dorpat 1879. — The genera 
treated here are: Synodontis, Monacanthus, Gasterosteus, and Triacanthus. 
