VARIATION IN TOAD AND ISOPOD. 



279 



rudiment of the spleen instead of a single one, as is normally the case. 

 Bearing this uncertainty in mind, we may provisionally include the present 

 case in the lienes accessorii of Haberer. 



Case 7. Lìgia sp., S£. With a supernumerary thoracic segment. 

 (Cut 8.) 



This isopod is a very common species found on our rocky coasts, and 

 on the banks of estuaries and the canals that open into them. It is more 

 nearly allied to L. italica than to L. oceanica, but I regret to say that, with 

 the literature at my disposal I 

 have not been able to identify it. 

 The sexes can easily be distin- 

 guished by the fact that in 

 the male the last thoracic seg- 

 ment bears, in the mesial portion 

 on the ventral side, a pair of long, 

 slender, needle-like processes pro- 

 jecting backwards, and that the 

 endopodite of the second abdo- 

 minal segment is transformed into 

 a long process resembling in shape 

 the claspers of certain skates. 



As in all isopods, the body 

 is normally made up of twenty 

 segments, as counted by the num- 

 ber of pairs of appendages, viz. six in the head, corresponding to the two 

 pairs of antennae, one pair of mandibles, two pairs of maxillae, and one pair 

 of maxillipedes, seven in the thorax, each bearing a pair of legs, and seven 

 in the abdomen, or pleon, of which the last two are fused together and 

 bear a pair of long bifid appendages, while the first five bear the ordinary 

 spurious legs. As shown in the accompanying cut, the example before 

 us has eight thoracic segments, but is normal in all other respects. 

 The thoracic segments are so exactly like those of normal examples, 

 that it is only by actual counting that one can make out that there is a 



Cut S. 



