350 GUDRUN RUUD 



Explanation of Plate. 



Plate X. 

 Fig. 1. Skin removed from the ventral side of the head of a 110 ram. em- 

 bryo, drawn, expanded on a waxplate — with the inner side up, 

 to show the 'groups of ampullae and the course of the sensory 

 kanals (X 5). 

 Fig. 2. The same from the dorsal side of the head {>< &)• 

 Fig. 3. Top-side view of a 60 mm. embryo, showing the pores of the sen- 

 sory and ampullery canals and the pit organs (X 5). 



Index letters. 



ba = buccal group of ampullae. 



ba = their tubes or pores. 



bu =■ ram. buccalis facialis. 



dp — dorsal pit line of the body. 



hma = hyomandibular group of ampullae. 



hma' = their tubes or pores. 



hmf = ram. hyomand. facialis. 



io = infra-orbital canal. 



'l = lateral canal. 



Ip = lateral pit line of the body (=„accessory lat. line", Allts (1)). 



s = tubules. 



so = supra-orbital canal. 



soa = superficial, ophthalmic group of ampullae. 



soa' = their tubes or pores. 



sof = ram. superficialis ophthalmicus facialis. 



stp = supra temporal pit organs. 



B = pectoral fin. 



End = auditory pore. 



G = gills. 



M =^ mouth. 



N = nasal aperture. 



Sp = spirale. 



= Eye 



Fig. 4. Diagram after Ewart ((30) PI. 11, fig. 2), introduced to admit of a 

 comparision between this and the lateral line system of Spinax. 



On my copy the suprabranchial nervebranches to the lateral line 

 system av darker drawn up than the other nerves and the diffe- 



