Kappers, Teleostean and Selachian Brain. 8 1 



owe so many excellent observations, unfortunately used this name 

 for a bilateral dorsal protuberance of almost the same size found 

 in some teleosts, viz., the cyprinoids, who^e two parts are some- 

 times completely fused in the median line (Cobitis fossilis, Carpio, 

 Barbus, Brama) and consequently appear as a single "tuberculum 

 impar," showing its bilateral origin only by a median groove 

 situated dorsally. This lobus trigemini of Mayser, however, 

 has no relation whatever to the lobus which is developed farther 

 frontally in the acoustic region, but is the continuation of the lobi 

 vagales and glossopharyngei, originating from a more posterior 

 and medial region. 



This region of Mayser is found in all teleosts as well as in all 

 selachians (of larger or smaller size in all fishes) and is the most 

 anterior part of the lobi vagales. From this region a medullated 

 bundle arises which runs for some distance in a frontal direction 

 immediately under the fourth ventricle and then leaves the brain 

 along with the motor facialis forming the sensory root (pars inter- 

 media) of this nerve as described above. This sensory root was 

 also found by Mayser, but since the lobe from which it originates 

 in some bony fishes has somewhat the same appearance as the 

 lobus trigemini of the selachians, this root was considered by him 

 as the equivalent of the so-called superior geniculated sensory 

 trigeminus root (from the "lobus trigemini") of the selachians. 

 In consequence he made two mistakes: (i) he considered the most 

 anterior part of the lobi vagales and the so-called lobus trigemini 

 of the selachians to be equivalent; and (2) in consequence of this 

 he identified the facialis root originating from these swellings in 

 the teleosts with a root from the "lobus trigemini" of the sela- 

 chians. Now, subsequently, it has appeared that the so-called 

 superior geniculated sensory trigeminus root of the selachians is not 

 a trigeminus root at all, but a lateral line root from a separate swell- 

 ing of the octavus region which peripherally joins the trigeminus. 

 For this root, the nervus lateralis anterior, there is no separate 

 swelling in the teleosts. This root innervates a canal system of 

 the head which probably has an important static function like the 

 lateral line of the body. 



Now, after this short exposition of facts and misconceptions I 

 can proceed with the description of the radix anterior lateralis, as 

 I shall call this most anterior static root, in agreement with 

 Johnston. After having entered the acusticum (Lophius, Fig. 



