196 PR WALTER M. TATTERSALL ON 



projects laterally and hides the plates from the dorsal aspect ; segments of the thorax 

 with four small, equally distant tubercles on the dorsal surface, the tubercles more 

 pronounced than in E. Kraussii ; a pair of larger tubercles in the centre of the combined 

 first three segments of the pleon ; terminal segment of the latter triangular in shape 

 with the apex somewhat produced but the actual tip rounded ; centre of the telsonic 

 segment evenly vaulted from a point some little way in from the margins, bearing in 

 the centre two pairs of large tubercles, the anterior pair slightly narrower and more 

 elongate than the posterior pair ; behind the latter in the median line are two smaller 

 tubercles, one behind the other; the lateral parts of the telsouic segment with a number 

 of minute tubercles or granulations ; a very light carina runs from the base of the median 

 tubercles to the apex of the telson ; inner and outer uropods shorter than the telson ; 

 apex of the inner one truncate, with the outer corner somewhat produced into a sharp 

 angle ; outer uropod almost sabre-shaped, apex sharpely acute. 



My report was almost completed when I received the large adult female specimen, 

 on which this description is based, from the Kev. T. R. R. STEBBING, who found it and 

 another example among some Decapod crustaceans from the same place. I had already 

 figured as the type the largest specimen then in the collection, a female, 6 mm., and I re- 

 produce that figure here because it illustrates the differences between the young and adult 

 of this species, and as a contribution to our knowledge of the changes which a Sphseromid 

 may undergo during growth. A comparison of the two figures will show that there is 

 considerable difference between the young and adult stages. In the young stage, the 

 telsonic segment is less produced and its apex more obtuse than in adult specimens. 

 It bears only the two pairs of larger tubercles of the adult stage, the two median 

 tubercles and the lateral minute tubercles being absent. The tubercles throughout the 

 body are less developed in the young stage. The differences in the uropods are quite 

 considerable. In the young example both uropods have more or less evenly rounded 

 extremities, quite distinct from the form of the uropods in the adult as described above. 



Having seen no male specimens, I am unable to say whether this species exhibits 

 any marked sexual differences. Otherwise the species seems clearly referable to the 

 genus Exospliseroma, as far as the characters of the mouth organs and pleopods go. 



The arrangement of the epimeral plates is quite characteristic. The first plate 

 projects forward under the eyes, the next four are rectangular or rhomboidal in shape, 

 while the sixth is larger than any of the others and projects backwards so as to almost 

 hide the small seventh plate. When the animal is doubled in two, the epimeral plates 

 form a very good protection for the sides of the body. 



The arrangement of the tubercles will allow the species to be recognised at once. 

 It differs from E. Kraussii in the more pronounced nature of the tubercles of the body, 

 in the possession of two pairs of large tubercles in the telsonic segment, and the shape 

 of the uropods, as well as in the form of the epimeral plates. 



I have seen a specimen of this species, unnamed, in the British Museum, from the 

 island of St Paul. 



(ROY. soc. EDIN. TRANS., VOL. XLIX., 886.) 



