400 Mr. F. Day on Orcynus thynnus {L.). 



these indicate the position of the true tube-walls. Middle 

 Devonian, Gerolstein. 



Fig, .5. Part of a tano-ential section of R. stromatoporoides, Roem., en- 

 larged twenty times. The specimen is in the " sfellhnicans" 

 state, hut the walls of the tubes are visible. The peculiar 

 rounded tubercles at the angles of junction of the corallites are 

 well seen. Middle Devonian, Gerolstein. 



Fiff. 6. Part of a vertical section of a double colony of H. stromatopo- 

 roides, Roem., partly in the normal condition and partly in the 

 " stellimicans " state, enlarged twelve times. Middle Devonian, 

 Gerolstein. 



Fi^|. 7. Part of a vertical section of another example of the same, simi- 

 larly enlarged. Tn this specimen the stellate crystallization has 

 not "been complete, and the centres of the tube-cavities are par- 

 tially unobliterated and exhibit the remains of the tabulae. 

 Middle Devonian, Gerolstein. 



Fi(j. 8. Part of the surface of B. stromatoporoides, enlarged forty times. 

 Minute elevations are seen at the angles of junction of the 

 corallites ; but these may be only the result of weathering. 

 Middle Devonian, Gerolstein. 



[To be continued.] 



XXXV. — N^ote on Orcynus tliynnus (L.). 

 By Feancis Day, F.L.S., F.Z.S. 



It is always satisfactory to obtain reliable records of rare or 

 little-known British fishes, especially when new facts have 

 been ascertained as to their geographical distribution, exter- 

 nal form or internal structure, &c. ; and I was therefore 

 pleased to see in your last month's issue a paper by Dr. 

 M'Intosh on a male tunny ( Orcynus thynnus) , 9 feet long, 

 trawled off Pittenweem, in Scotland. In that paper some 

 criticisms are offered upon my work on ' British and Irish 

 Fishes ' and on my figure of the tunny, which observations I 

 propose briefly replying to so far as they affect myself. 



But I must first observe that as no figure of this new speci- 

 men is given, while the number of fin-rays is omitted, no 

 evidence is offered, except as to the size of the fish, that it was 

 the tunny {Orcynus tliynnus)^ or the bonito [Thynnus pelamys)^ 

 or even T. thunmna, which has been captured more than 

 once off Denmark. An essential difference between the fishes 

 forming the restricted genera Orcynus and Thynnus consists 

 in those pertaining to the first having " small teeth on the 

 iaws, vomer, and palatine bones," while in the second there 

 are '' small teeth on. the jaws, palatine bones, but none on the 

 vomer^ Dr. M'Intosh observes of his example: — "The 



