characters of the Araneiform Crustacea. 3 



tubercle arises from the centre of the first thoracic segment and 

 projects forward, inclining very considerably over the rostrum ; 

 its extremity is blunted, and the eyes, which are four in number, 

 are placed near the apex. A thin narrow projection arises from 

 the anterior edge of the first segment immediately before the tu- 

 bercle, and is continued beyond the middle of the rostrum. The 

 palpi are eight-jointed (PL I. fig. 10). 



NympJwn Johnstoni*. 



The ocular tubercle in Nymphon arises in all the species from 

 the posterior edge of the segment. In this species it is bent from 

 the middle backwards, at which point the eyes are situated ; the 

 apex is pointed. The palpi are four-jointed (fig. 14). The ovi- 

 ferous legs are eleven-jointed, including the claw (PL I. fig. 15). 

 The two tarsal joints are of equal length (fig. 16). 



NympJwn spinosumf. 



In this species the ocular tubercle projects backwards from the 

 base, the superior extremity is rounded, and the eyes are arranged 

 round a projecting edge (PL I. fig. 17). 



The first joint of the tarsus is about half the length of the se- 

 cond (PL I. fig. 18). 



Nymphon pellucidum % . 



The ocular tubercle in this species is rather short, its extre- 

 mity is obtuse and rounded, and the eyes are situated a little di- 

 stance from the top (fig. 19). 



Nymphon similis (n. s. mihi) . 



The ocular tubercle is depressed and projects backwards (PL I. 

 fig. 21). It will be observed that this organ, in all the species of 

 the genus Nymphon, is situated at the posterior extremity of the 

 first thoracic segment, and also that it never projects forwards. 



EXPLANATION OF PLATE I. 



Fig. 1. Profile of the rostrum and first thoracic segment of Pycnogonum 



BaUenarum. 

 Fig. 2. Abdominal surface of same parts with the oviferous leg of one side. 

 Fig. 3. Profile of Phoxichilus. 



Fig. 4. Under or abdominal surface of same parts in Phoxichilus. 

 Fig, 5. Tarsus of Phoxichilus with portion of last tibial joint. 

 Fig. 6. Profile of Phoxichilidium coccineum. 

 Fig. 7. Abdominal surface of same parts with the oviferous leg of one side. 



* Jameson's Edinb. Phil. Journ. vol. xxxii. p. 138. pi. 3. fig. 5. Through 

 some error, the proper references to the plate in the journal quoted have 

 been misplaced. 



f Jameson's Edinb. Phil. Journ. vol. xxxii. p. 139. pi. 3. fig. 3. 



X lb. vol. xxxii. p. 138. pi. 3. fig. 6. 



B2 



