Vol. 52.] ANNIVERSARY ADDRESS OF THE PRESIDENT. XCU1 



In 1870 I described what I believe to be a portion of a fossil 

 Amphipod from the Lower Ludlow Rocks of Leintwardine, Shrop- 

 shire, under the name of Necrogammarus Salweyi ; it is not quite 

 certain whether Gampsonyoo fimbriatus^ Jordan, from the Coal- 

 Measures of Rhenish Prussia, is correctly assigned to this division, 

 but I am inclined to retain it here, however, as its most natural 

 position. Mr. Spence Bate has named and described a species of 

 Amphipod as Prosoponiscus problematicus, from the Magnesian 

 Limestone of Durham. 



Other fossil forms occur in the Tertiary rocks and are mostly 

 referable to existing genera such as Gammarus, G. oeningensis, 

 from the Miocene of (Eningen; and Palceogammarus sambiensis, from 

 the Baltic amber deposits, etc. 



Isopoda. — This division of the Malacostraca is marked by the 

 persistence of the seven pairs of ambulatory thoracic limbs, which 

 never bear the gills attached to their bases as in the Amphipoda, 

 but the appendages of the abdomen take on this function, being 

 specially modified into leaf-like branchial organs and do not take 

 part in locomotion, save in the swimming forms. The members 

 of the group are for the most part of small size. Many of the living 

 Isopods are attached to fishes and Crustacea, and one parasitic fossil 

 form is known (Bopyrus). 



Numerically, the order is large and very widely distributed geo- 

 graphically, consisting of walking, running, and swimming forms ; 

 and lastly of sedentary parasitic forms — of these it is the female only 

 which remains fixed, the male being often peripatetic in his habits, 

 passing from female to female. Many Isopods — e. g. the Oniscidae 

 — live habitually on land, breathing air, which it is necessary should 

 'he fairly moist ; hence they usually frequent damp situations, 

 -under decaying wood and leaves, and beneath stones. The Sphaero- 

 midas frequent rocky shores, and run and swim with considerable 

 agility. Many forms of Isopoda are strictly marine, some occurring 

 at great depths (over 2000 fathoms). Some few Isopods have been 

 met with of larger size than the average members of the group. 

 One. dredged by Prof. Alexander Agassiz, during the cruises of the 

 1 Blake/ from a depth of 955 fathoms on the north-east of the bank 

 of Yucatan, and north of the Tortugas, named Bathynomus giganteus 

 by Alph. Milne-Edwards, measures 9 inches in length by 4 in 

 breadth, and far exceeds any other living species in size. Not- 

 withstanding the vast depth from which Bathynomus was obtained, 

 the eyes are well developed, but instead of being placed upon the 

 upper surface of the head as in all known wandering Cymothoidae, 



