VOL. XLV.] PHILOSOPHICAL TRANSACTIONS. 511 



has penetrated the cells of the nautilus while in its natural state. The diaphragm 

 or partitions remain still distinct and visible. The different colour of the stony 

 matter in some cells of a dark brown or hair colour, in others of a light brown or 

 ash-colour, with the natural polish of the oiitside, gives it a beautiful appearance ; as 

 it is represented in fig. 5, pi. Q, where it is drawn of its natural size in 3 different 

 views ; viz. a shows the side view of it -, b the fore part ; c the back part. CM. 

 It was found in Pool's Hole in Derbyshire. Its sutures or diaphragms re- 

 semble those of some of the larger cornua ammonis ; but its shape bespeaks it to 

 be a species of nautilus ; and it is thought to be a non-descript, both in its natu- 

 ral and fossil state. 



On the Roach kept in Glass Jars. By Mr. IVm. Arderon, F. R. S. 



N"487, p. 321. 



Of all the several kinds of fish which for some years Mr. A. kept in glass jars, 

 none seems more impatient of imprisonment than the roach ; nor if they are well 

 looked after, and supplied often enough with fresh water, did he observe any, 

 except the roach, to become distempered. But most commonly, after this fish 

 has been a little while confined, the finny part of its tail begins to drop off piece 

 by piece ; and when the finny part is all gone, a sort of mortification seizes on 

 the tail itself, and gradually creeps along till it reaches the intestines, at which 

 time the fish immediately dies. 



The last roach he had under this disorder was about the beginning of January ; 

 when in the space of a month, it had lost the greatest part of the fin, which in- 

 duced him to clip off the rest, hoping thus to stop the progress of the mortifica- 

 tion. But this was of no manner of service : the distemper still gained ground ; 

 and as it increased a fine fibrillous substance grew out from it. These fibrils, 

 when examined by the microscope, show themselves to be a number of minute 

 tubes, filled with a brownish liquor ; which on pressing them, becomes imme- 

 diately discharged. 



When first he perceived this fibrous substance inveloping the fish's tail, he 

 supposed it to be nothing but a mouldiness, of that kind which frequently is seen 

 on decayed flesh and fish ; but on trial he found it to be of a much stronger tex- 

 ture and consistence than such mouldiness is ever known to have ; for though he 

 several times let a full stream of water run upon it from a cock, he could never 

 wash it off. 



he was called to the bar; which however he afterwards quitted, taking holy orders, and in 1747 

 was appointed one of the king's chaplains. The year following he was made dean of Exeter, and in 

 176'2 bishop of Carlisle ; and he died in 1768. 



Dr. Lyttelton was for many years president of the Society of Antiquaries, and contributed many 

 valuable articles to the Archseologia. 



