640 D)\ R. H. Traquair — New Fuh Remains from Borough Lee. 



tlie water there is sufficient proof. In 1772 lightning attacked the 

 Eiver Doubs, near Besan^on, and stunned the fish, which were 

 floated along by the stream. In 1670 a lightning flash fell on the 

 Lake Zirknitz, in Austria ; and such a quantity of fish almost 

 immediately floated upon the surface that the neighbouring inhabit- 

 ants collected twenty-eight waggon-loads for manure" [Chambers's 

 Journal, October 2, 1869, p. 688). 



5. Though by no means so extensive in effect as any natural 

 explosion of volcanic ashes, steam, and noxious gases, yet the 

 operations of sub-marine explosions, by torpedoes, common blasts, 

 etc., have analogous effects ; and even in such experiments in lakes 

 and rivers the workmen look out for the dead fish remaining near 

 the place of the explosion. 



In Nature, November 26, 1874, an explosion by means of nitro- 

 glycerine on the Oregon coast is mentioned by Mr. Chase, who 

 states that many fish were killed thereby, and others were taken in 

 a stunned state. 



XI. Marine life surviving in freshwater lakes. 



The changes that take place in a local fauna and flora by a marine 

 lagoon being cut off and in time converted into a freshwater lake 

 are in some degree analogous to the more sudden and extensive 

 destruction of marine life, by the causes above mentioned ; but many 

 creatures gradually get accustomed to new conditions, and therefore 

 the whole assemblage is not swept away at once. Many interesting 

 notices of such occurrences have been made. See Nature, vol. i. p. 

 454 ; vol. xiii. p. 107, etc. 



. III. — Notice of New Fish Remains from the Blackband 



Ironstone of Borough Lee, near Edinburgh. — No. III. 



By Dr. R. H. Traquair, F.R.S., F.G.S. 



Selachii. 



Pleuracantlius gracillimus, n.sp. 



LENGTH of a typical spine H inches ; greatest diameter, 

 iV inch. The spine is thickest about half an inch from 

 its proximal extremity, towards which it slightly contracts, while 

 distally it tapers to a fine point ; its contour is at first straight, 

 then becoming gently curved backwards towards the apex. Trans- 

 verse section at first round, but near the middle of the spine a 

 flattened area commences, running along the posterior margin, and as 

 this is followed onwards, a delicate median ridge appears, and is 

 continued to the apex. Along the boundary, on each side, of this 

 posterior area, a right and left row of denticles is seen extending 

 from the apex to three-quarters of an inch from the base : they thus 

 occupy a greater extent of the length of tiie spine than the area in 

 question. These denticles are about 38 on each side, opposite, 

 closely set, minute, their bases compressed and proportionally elon- 

 gated, their sharp, conical points directed obliquely downwards. 

 Surface of spine striated proximally by delicate longitudinal grooves, 

 which become gradually lost towards the perfectly smooth apex. 



