PECULIAR HABITAT OF A PYCNOGONID. 1 95 



specimens of undoubted Endeis spinosus from the Norwegian 

 coast and from Plymouth, respectively. Furthermore, I have 

 had one specimen, labelled "Phoxichilus vulgaris,'' which I feel 

 confident came from Naples, although no locality was given on 

 the label. My reasons for believing that this specimen came from 

 there are twofold: First, because it was with other Mediterra- 

 nean pycnogonids, and second, because the name vulgaris, which 

 European writers unanimously consider as a synonym of spinosus, 

 has been used for this species only in that locality. Finally, 

 in addition to those from Vineyard Sound I have from the 

 American side of the Atlantic a number of specimens of Endeis 

 from the Tortugas, Florida. One of these I collected myself; 

 the others were kindly sent to me by Dr. A. G. Mayer, director 

 of the Marine Laboratory of the Carnegie Institution. 



After having compared carefully the specimens from these 

 five widely separated localities, viz., Naples, Plymouth, Norway, 

 Vineyard Sound and the Tortugas, I am forced to the conclusion 

 that in spite of their range and their difference in habitat, they 

 in reality must all be considered as belonging to a single species, 

 Endeis spinosus (Montagu). The Vineyard Sound specimens, 

 it is true, appear in general a little stouter than those from 

 Norway, due to the legs being proportionately a trifle shorter; 

 this difference, however, is not great and is inconstant. The 

 following table presents a number of proportions, based usually 

 on the average of measurements of all the legs of from one to three 

 or four specimens from each locality. The numbers of speci- 

 mens measured were so small and the results are in general so 

 irregular that not much importance can be attached to them. 

 It will be noticed that in the proportion of the length of the 

 femur to that of the coxal region, there is a gradual relative 

 shortening of the femur as one goes from Naples up the European 

 coast and down the American side to the Tortugas; the same is 

 true in a general way for the relation of the trunk to the pro- 

 boscis ; while the relation of the trunk to total leg length is more 

 irregular. This gradation in two of the cases may or may not 

 have any real significance.' 



^ Owing to the comparatively small amount of differentiation in the four pairs 

 of walking legs of the pycnogonids and to the fact that they present characters 



