No. 12. — Reports on the Eemlts of Dredging, under the Supervision 

 of Alexander Agassiz, along the East Coast of the United States, 

 during the Summer of 1880, hj the U. S. Coast Survey Steamer 

 "Blake," Commandek J. E. Bartlett, U. S. N., Commanding. 



(Published by permission of Carlile V. Tatterson, Supt. U. S. Coast and 

 Geodetic Survey.) 



XIII. 

 Report on the Pycnogonida, by Edmund B. Wilson. 



The specimens described in the following pages were dredged by Mr. 

 Agassiz, during the summer of 1880, off the eastern coast of the United 

 States, in a region extending from South Carolina to the northeastern 

 extremity of St. George's Banks, lying between N. Lat. 31° 57' and 

 41° 35', and W. Long. 78° 18' and 65° 35'; the range of depth was 

 from 73 to 1242 fathoms. 



It was at first intended to include descriptions of the Pycnogonida in 

 the report on the Crustacea from the same region, which is in course of 

 preparation by Professor Smith, of Yale College. Upon examination, 

 however, the collection was found to possess features of considerable in- 

 terest ; and, though the species are few, they seem to merit independent 

 description and illustration. The most striking feature of the collection 

 is the remarkable size of most of the forms, which may fairly be called 

 colossal in comparison with shallow-water or littoral species. Of the 

 three species of Colossendeis (two of which are apparently undcscribed) 

 the smallest has a span of 14 cm. between the tips of its outstretched 

 legs, while the 'largest has an extent four times as great. The new 

 gQxin^ Scceorhynchus has an extent of more than 19 cm., — a gigantic 

 size as compared with the dimensions of its nearest allies. The most 

 abundant species of Nymphon is the largest of that extensive genus ; 

 and one species of the new genus Pallenopsis is more than twice as large 

 as any of the species of allied genera [Pallene, Phoxichilidium, Anoplo- 

 dactylus), which are known only from the littoral zone or comparatively 

 shallow water. 



It is, further, interesting to note that in a number of forms the visual 



VOL. VIII. — NO. 12. 



