MUSEUM OF COMPARATIVE ZOOLOGY. 249 



more numerous and larger in the male. Terminal joint claw-like, very short 

 and stout. 



Ambulatory legs (in the female) about three times as long as the body (without 

 the rostrum), slender and tapering ; 2d joint about two and one half times the 

 1st or 3d, with a slight but characteristic elevation on the anterior side outside 

 the middle ; 4th and 5th, longest, equal ; 6th, two thirds the fifth ; 7th, one 

 third the 6th ; 8th, less than 7th ; dactyli (Fig. 29) very short and small; those 

 of the anterior pair of legs are considerably smaller than the others, but are 

 unmistakably present (compare Gnamptorhynchus). 



In the male the legs are relatively shorter. The whole surface is granular 

 with fine close-set tubercles. Color pale dull yellow to dusky, sometimes 

 irregularly mottled with yellowish and dingy chocolate-brown. 



As shown by the measurements, the sexes differ conspicuously in size. 

 Female: — Length of body (not including rostrum) .... 30.5 mm. 



" rostrum 17 " 



" antenniE 5.8 *' 



" palpi 35.5 " 



" accessory legs 36 " 



" ambulatory legs 90 " 



Male : — Length of body 22 " 



legs 58 " 



Four males and five females from locality 308, N. Lat. 41° 24' 45", W. Long. 

 65° 35' 30", 1242 fathoms. 



This is an interesting species. The accessory legs, as noted above, arise from 

 distinct lateral processes, near the middle of the oculiferous segment. The 

 palpi also are attached to prominent processes of the same segment. The 

 presence of well-marked sexual characters in the "antennae" has not before 

 been observed in the group. The male seems for some reason to retain the 

 larval chelate antennaj, which undergo in the female a further retrograde de- 

 velopment, and become fmictionally useless. 



I cannot absolutely demonstrate the specific identity of the two forms de- 

 scribed as male and female, though there can be scarcely a doubt that they are 

 of the same species. They are all from the same haul, agree in every respect 

 except size and the structure of the antennae and accessory legs; and the differ- 

 ences of the latter correspond with those known to exist among other Pycno- 

 gonida. The sexes were determined by examination of the internal generative 

 organs. 



The chelate or simple character of the "antennae" is commonly accepted 

 as a family character, but the small value of such a distinction is shown by 

 the structure of this species. A very slight further reduction of the antennae 

 iu the female would bring the latter into the Achelida;, as now defined, while 

 the male falls into the Nymphonidce. The need for an entire re^^sion of the 

 systematic arrangement of the Pycnogonida is sufficiently obvious, but no ac- 

 ceptable one seems possible until our knowledge of the development is more 

 complete. 



