Messrs. Hancock & Howse on Janassa bituminosa. 47 



first tliree and most constant segments of the head represented 

 by their appendages, though these are diminished to a very 

 minute size, so as not, in P. orthagorisci^ to be visible to the 

 unassisted vision. As we also find four out of the five pairs 

 of thoracic appendages present, it is pretty plain that it is 

 chiefly the ordinary oral appendages, or rather those appen- 

 dages usually modified for the purpose of assisting in the pre- 

 hension and mastication of food, that become altered into the 

 strange-looking arborescent follicles met with around the 

 mouth. 



EXPLANATION OF PLATE I. 



Fig. 1. Pennella orthagorisci, J , natural size. (The specimen has shrunk, 



from being preserved in spirits.) 



Fig. 2. Head, enlarged, dorsal aspect. 



Fig. 3. The same, ventral aspect. 



Fig. 4. Eye-spot (a), antennules (b), antennas (c). 



Fig. 5. Anal orifice. 



Fig. 6. Head of second specimen, showing the comparatively short horns. 



VIII. — On Janassa bituminosa, Schlotheim^ from the Marl- 

 Slate of Midderidge, Durham. By Albany HaNCOCK, 

 F.L.S., and Eichard Howse. 



[Plates II. & m.] 



Through the obliging kindness of Joseph Duff, Esq., who 

 has been for many years actively investigating the fossil flora 

 and fauna of the south of Durham, we have lately had an 

 opportunity of thoroughly examining the structure of the jaw- 

 teeth and shagreen skin of this most interesting addition to the 

 fauna of the English Marl-slate, which is the exact equivalent 

 of the German Kupferschiefer. 



Four groups of these remarkable jaw-teeth have been ob- 

 tained by Mr. Duff at Midderidge — the first group in the year 

 1865, and the others during the autumn of the present year, 

 1869. These are, we believe, the first and only specimens 

 that have been discovered in England. 



But in Germany this species has been frequently found in 

 the Kupferschiefer, which is very much worked, on account of 

 the valuable copper-pyrites which it contains, in numerous 

 localities ; and consequently the general appearance of these 

 teeth must be well known to those who are familiar with tlie 

 works of Schlotheim, Miinster, Geinitz, and others. Accord- 

 ing to the last-named author, the beautiful specimen still 



