Thomson. — On Netv Zealand Crustacea Anomura. 195 



maxillipedes, on which Leach founded the latter genus, and 

 on which Miers and Henderson lay so much stress, is after all 

 a comparative one. In several large males of Municla the 

 joints all show the flattened and foliaceous form characteristic 

 of Grimotliea, as well as the densely fringing setae, while in 

 one large female the joints are completely foliaceous. To 

 show the relative lengths of the parts in the two forms, I 

 append a table of measurements of a few individuals taken at 

 random. The length is measured from the point of the ros- 

 tral spine to the extremity of the caudal fin ; the rostral 

 (median) spine is measured from the base in the front region 

 of the carapace. The first three specimens of Munida were 

 taken from Otago Harbour, the fourth from Paterson Inlet ; 

 those of Grimothca were all caught in Otago Harbour, but at 

 different times. The measurements are in millimetres : — 



Length. 



Rostral 

 Spine. 



Right 

 Chelipede. 



Antenna. 



External 

 Maxillipede. 



Munida subrugosa. 



<? 

 ? 



35 

 39 



24 

 30 



21 

 21 

 20 

 12 



Grimotliea gregaria. 



I might multiply these examples by scores, but the result 

 would remain much the same. The relative length of the 

 body to that of the external maxillipedes is about 5 to 2 in 

 Munida and 5 to less than 3 in Gritnothea. The sexes are 

 usually present in about equal proportions in shoals of Grimo- 

 tliea, a lot of seventeen taken at random from collections 

 made in Dunedin and at the ocean beach north of Otago 

 Heads gave eight males and nine females. 



Out of a large number of specimens of Grimothea all had 

 the pair of spines at the sides of the median line of the 2nd, 

 3rd, and 4th abdominal segments, said by Miers (I.e.) to be 

 characteristic of Munida. On the other hand, several male 

 specimens of the latter wanted the characteristic " spine on 

 either side of the middle in the gastric region," while in some 

 females they were but slightly developed. 



Until, then, the life-history of these Crustaceans is worked 

 out I am inclined to treat Grimothea gregaria as merely a 

 stage in the development of Munida subrugosa. 



