296 Prof. M'lntosh's Notes from the 



the Bed Crag of Woodbridge (Brit. Mus. nos. 43328, P. 5582). 

 These arc more laterally compressed than the vertebrae of 

 Thynnusscaldisiensis, and differ remarkably in the stouter and 

 broader proportions of the ridge between the lateral fossa?. 

 Discoveries in the Eocene render it probable that these fossils 

 represent some early Tertiary genus at present undetermined. 



XLII. — Notes from the St. Andrews Marine Laboratory 

 {under the Fishery Board for Scotland). — No. XI. By 

 Prof. M'Tntosh, M.D., LL.D., F.P.S., &c. 



1. On the Occurrence of the Hydro-medusae and Scyphomedusse 



throughout the Year. 



2. On Arachnactis. 



1. On the Occurrence of the Hydromedusa, •and Scyphomedusce 

 throughout the Year. 



In examining the Medusas three nets were often used 

 simultaneously, viz. surface, midwater, and bottom, and no 

 special apparatus was at any time employed for the closure of 

 the two latter during descent and ascent. Fairly reliable 

 observations, however, were made, with regard to the bathy- 

 metrical distribution of these pelagic organisms without the 

 latter arrangement, as proved by the fact that each net occa- 

 sionally had a fauna of its own, and that, as the season 

 advanced, certain forms which at first were near the bottom 

 appeared by- and- by in the midwater- and finally in the sur- 

 face-net. In August 1888, for instance, the surface-net was 

 less rich in species of Hydromedusse than either of the others, 

 though certain forms occurred in great abundance, a transfer- 

 ence of the latter from the lower regions of the water having 

 taken place. 



It is possible that some of the forms subsequently mentioned 

 may pertain to the same Hy droit! stock, representing perhaps 

 younger and older stages or mere variations j but as our 

 knowledge of the group, though largely added to by the 

 labours of Allnian, Agassiz, Hseckel, Hincks, and others, is 

 still in need of improvement, it has been considered advisable 

 to follow to a certain extent the descriptions of Forbes. No 

 gonozooid of Coryrnorpha, which occurs in considerable 

 numbers on smooth ground off the Budda Rock, has yet been 

 obtained. 



In contrasting in August the fauna of the bay with the 

 offshore in the neighbourhood of the Bell Pock, the greater 



