PYCNOGONIDS 253 



surprising if a correlation were found in their distribution. In this 

 connection the results presented in the table may have some bear- 

 ing on the question of a line of demarcation at the Shumagin 

 Islands. The evidence does not favor such a distinction, for it 

 will be noticed that of the two forms obtained at Orca, both are 

 found at Popof Island, and one of them at Unalaska, still farther 

 west. 



As might perhaps be expected, all the species from California 

 are different from those found in Alaska ; but in determining the 

 position of the dividing line between the two faunas the data at 

 hand give no help, although, as Nutting supposes, it is not at all 

 unlikely that the line is not far to the southward of Puget Sound. 



The fauna of the California coast is in some respects strikingly 

 like that of the Gulf of Naples. For instance, two representatives 

 of the genus Ammothella are found along the coast of that State, 

 and none to the northward, while of the other four species which 

 apparently belong to this genus (see p. 273), but which have here- 

 tofore been referred to the unrestricted genus Ammothea, three 

 are recorded from Naples by Dohrn ( J 8i), and one from the Ber- 

 mudas by Verrill (: 00). The genus Clotenia is known only from 

 the original species, C. conirostris Dohrn, from Naples, and C. 

 occidentalis from Pacific Grove, California. This similarity in the 

 faunas of the two places is probably brought about merely by the 

 similarity in temperature rather than by any direct faunal relation, 

 as a similarity can be found between the forms occurring on the 

 coast of California and those of any place having much the same 

 thermal conditions. For example, the two previously known 

 species of Lecythorhynchus have been recorded only from Japan, 

 where the conditions are much the same as on the California 

 coast. 



CLASSIFICATION AND TERMINOLOGY. 



The classification of the Pycnogonida is at best very unsettled. 

 The group as a whole is remarkably homogeneous, the classifica- 

 tion depending for the most part upon such characters as the 

 development or non-development, or the loss in adult life, of 

 certain of the anterior appendages. Other differences are often 



