4 ARKIV FÖR ZOOLOGI. BAND 10. N:0 8. 



as that now in use. Ventral arches are developed on all the 

 praecaudal vertebrae (Hollard's »fausses apophyses trans- 

 verses»). On the anterior vertebrae they insert rather dor- 

 sally, but their insertion is gradually displaced more ven- 

 trally in the posterior region. In the caudal region haemal 

 arches are formed. According to Cuvier ribs are absent, but 

 Hollard and other authors state their presence. Regan 

 has pointed out that the so-called ribs are i>intermuscular 

 bones» (»epipleurals», »Fleischgräten»), a view which I have 

 found correct. The dorsal arches of the first vertebra do 

 not touch each other, but point cranially and börder the 

 occipital foramen of the skull. Regan has made a mistake 

 in this point. He refers the Balistids to the group »Sclero- 

 dermi», which he characterizes by vertebrae the neural ar- 

 ches of which form a single spine. That as I have shown is 

 not the case in the Balistids, which have a double neural 

 spine on the first vertebra. The dorsal arches of the other 

 vertebrae coalesce in the median line to a single spine. The 

 last caudal vertebra is quite symmetrical. No genetical stu- 

 dies have been made. 



Triacanthidae. 



Regan writes about the Triacanthids (p. 287): »praecau- 

 dal vertebrae with parapophyses from the third or fourth 

 to the last, epipleurals present». I have not had an oppor- 

 tunity to examine any specimen belonging to this family. 



Triodontidae. 



The vertebral column of the Triodontids seems to be of 

 a very interesting structure. As I have not had an opport- 

 unity to make any researches of my own on this subject, I 

 must confine myself to quoting earlier authors. Dareste 

 states the number of vertebrae to be 20 in Triodon maculatiis. 

 The two anterior vertebrae lack neural spines according to 

 him. HoLLARD, on the contrary, denies the presence of a 

 »spina bifida.» Which of these two views is the correct one, 

 is not a matter of any special interest; while it would be 

 of great importance to verify Dareste's statement about the 



