I. Synopsis op the Pycnogonida of New England. 
By Edmund B. Wilson.* 
Read, March 20th, 1878. 
It is the object of this paper to present a systematic synopsis of 
the species of Pycnogonida occurring on the coast of New England, 
including also those found as far north as Halifax, based on a study 
of the large collection of these animals in the Peabody Museum of 
Yale College. My thanks are due to Professor S. I. Smith for much 
valuable aid, particularly in the use of his library, and to Professor 
Verrill, to whom I owe the opportunity of studying the group, for 
suggestions and other assistance. Many of the specimens were col- 
lected by the U. S. Fish Commission, and to Professor S. F. Baird, 
the Commissioner, I am also indebted for the use of several figures, 
drawn by Mr. J. H. Emerton. 
In the Pycnogonida the body is composed of four apparent segments, 
which are expanded laterally into prominent processes to which the 
legs are articulated. The abdomen is rudimentary and presents no 
trace of segmentation, except in one or two forms, where it is bi- 
articulate. Upon the dorsal surface of the anterior or oculiferous 
segment is a prominent “ oculiferous tubercle” upon which are situ- 
ated the four simple eyes. 
The most anterior pair of appendages, which are wanting in the 
family Pycnogonidae, are in this paper regarded as antennae. These 
appendages apparently correspond to the chelicerae of spiders and 
scorpions, the homology of which is uncertain, since they are re- 
garded as antennai by some writers, while others consider them post- 
oral, and as probably representing the mandibles. In the higher 
forms they are composed of three joints and are often chelate; in 
other genera they are two-jointed, and in Tanystylum become re- 
duced to a single knob-like joint. 
Below the antennae is the proboscis or rostrum, which is often of 
great size; at its extremity is the triangular mouth, which is provided 
* Abstract of a graduation Thesis presented to the Governing Board of the Sheffield 
Scientific* School of Yale College, 1878. 
Trans. Conn. Acal>., Vol. V. 
July, 187 s. 
1 
