OF ORTHAGORISCUS MO LA. 239 



orifice ; spleen small and dark-coloured ; urinary bladder 

 very large, the urethra not terminating in the anus, but open- 

 ing externally by an orifice peculiar to itself, a little behind 

 the anus.^'' 



I have only seen two other specimens of the Orthagoris- 

 cus mola; one is preserved in the Museum of the Royal 

 Dublin Society ; it is much smaller, and its depth is greater 

 in proportion to its length than in the example before us : 

 the other, Mr. Robert Ball has very kindly given me permis- 

 sion to exhibit to the Society this evening ; it is evidently a 

 younger fish ; it agrees, however, in every particular except 

 in size, with the specimen before us. 



In a communication which I have very recently had with 

 Mr. Ball, he says "between the years 1818 and 1825, I saw 

 five of these animals off the coast of Youghal ; three were 

 dead, and two of them are in my possession, the specimen I 

 send is the larger." "Considerable difference exists in the 

 thickness and other proportions of the caudal portion of the 

 animal ; in the young it is very thin ; the bony tubercles are 

 also probably much dependent in number and size upon age. 

 A specimen which I saw in Professor Harrison's Museum, 

 only a few inches long, was much more like the figure in 

 Yarrell's work. There seems to be a regular gradation from 

 his, through mine, up to the specimen contained in the Muse- 

 um of the Natural History Society." 



In conclusion then, it would appear that the specimens of 

 Orthagoriscus mola which have been figured and described 

 by British writers, were young fish, whereas the subject of 

 my present communication is evidently a nearly fiiU-grown 

 animal ; and this will sufficiently explain the reason why their 

 descriptions and figures do not tally in every respect with 

 the specimen upon the table. It does not appear to me to 

 be at all necessary (as a member of our Society seems to 

 think), that we should look out for some new genus to place 

 it in. Its characters agree in every particular v^dth those of 

 the genus Orthagoriscus, as laid down in one of the latest 

 and best works upon British Animals, ' Jenyns' Manual ; ' 

 and that it is the Orthagoriscus mola, I have the additional 

 authorities of Mr. William Thompson, Mr. Robert Ball, and 

 Mr. Wilde, all of whom have carefully examined it, and 

 whose opinion upon such a point, no person in Dublin is 

 competent to call in question. But if additional evidence 

 be wanting, I may mention, that the four species of Entozoa 

 which occurred in it, are identical with those found in the 

 Orthagoriscus mola by Cuvier, Rudolphi, and Bremser ; and 



Vol. IV.— No. 41. n. s. 2 i 



