1:2 JOHAN KI^ER. |>i-x. AKCT. EXP. FRAM 



In Hie example- of Mcr<>i>. Scln'ii \ \ri> us \ve see on the right 

 -ide that the po.-t-orhilal canal at the hinder part hends slightly iuward- 

 and taper-. I cannot see, however, that they then proceed downwards 

 with funnel shaped openings as in the ca-e of rapheidoldbis. On tlie 

 other hand we can see that from the hinder point of the occipital canal 

 a new canal runs with a slightly arched direction outwards and 

 rearwards to the hinder margin of the cranial roof. In my opinion 

 tins appear- to he the beginning of the lateral line canal. A- 

 i- well known a similar condition is seen in the case of a numher of 

 coccosteomorphous fishes, and is therefore a further proof that the entire 

 head shield of Macropetalichthys contains only the cranial roof. 



The sensory canals which have a breadth of ahonl I mm. an 

 very clearly discernable in the specimen before us. owing to the circum- 

 -tance that the bone substance has almost entirely fallen away. A.- i- 



. 



well known, the canals in this genus are so deeply embedded in the 

 dermal plate.-, that in the form before us they appear on the under side 

 of the cranial shield like ridges. They open upwards by means of a 

 -ries of pores, which appear to be found only on the outer side of 

 the canal.-. They are easily discernable along the outer side of the 

 right post-orbital canal and for a short distance along the right supra- 

 orbital canal, inside the orbits. At the former place they are round, 

 with a cross section of 0.3 0.4 mm., and at the latter, where the entire 

 bone substance has been preserved, they are oval, about 0.4 ft.-) mm. 

 in length, and O.I mm. in breadth. 



The specimen also clearly shows the impression of an extensively 

 branched and line canal system on the inner side of the cranial roof 

 Ipl. I. fig. 4). As far as I can understand the.-e fine canal.- do not 

 appear to have had anything to do with the sensory canals, but may 

 possibly be vein- that have been embedded in the cranial bone-. I have 

 not been able to find anything corresponding to them in description of 

 Ihe other form- known of this genii-. 



Orbits. The.-e are 111 the mam discernable, although the foremost 

 portion ol the cranium i- defective. <)u the left side the length mav 

 be determined at I I .> mm. ; it is more difficult to determine the breadth, 

 hut presumably it may be placed ;it T.o mm. 'The orbits may therefore 

 be reconstructed as shown in the drawing, tig. '2. They thus appear 

 to have been inin-iiallv large and lengthy. 



Mori /on. I'Yoin the /one Dh in marin facies, (ioose Fiord. 

 Kile-mere Land. 



