344 Miscellaneous. 



posteriorly and internally to the second pair, to minute processes 

 springing from the ventral arc of the oculigerous somite and meeting 

 in the middle line : they are composed of ten joints, of which the 

 first is minute, the two next equal and cylindrical ; the fourth greatly 

 elongated and just perceptibly expanded at the apical end ; the fifth 

 short, scarcely longer than the second of the two basal joints, and 

 curved ; the sixth is likewise greatly elongated, but more expanded 

 at the apex and longer than the third ; the four terminal joints are 

 short, slightly decrease in length from the first to the last, which 

 comes suddenly to a subacute incurved point forming a sort of claw, 

 are curved, fringed on their inner andconcave margins with cilia and 

 minute spinules, and capable of being coiled tightly together so as to 

 form a prehensile organ. 



Both pairs of appendages are elbowed at a short joint intercalated 

 between two long ones, viz. the second pair between the second and 

 fourth, the third between the fourth and sixth joints. 



In many other species the terminal joints of the third pair of 

 cephalic appendages (pedes accessorii) will probably be found to be 

 similarly modified as a prehensile organ ; an examination of 0. F. 

 Midler's faithful figures of Nymphon grossipes, Fabr., in the 'Zoolo- 

 gia Danica '* would, in fact, alone suffice to show the existence of 

 such a modification in that species, even if Kroyer f had not described 

 it in his diagnoses of the genera Nymphon and Zetes, without, how- 

 ever, offering any interpretation of the structure. 



The oculigerous somite has its anterior margin straight, and is but 

 faintly constricted in front of the eye-tubercle. 



The first thoracic somite, if its distinctness from the oculigerous 

 somite be admitted, is very short. Of the remaining somites the 

 second and third are subequal, the former being, if any thing, the 

 longer, are as perfectly cylindrical and nearly as long as, but slightly 

 stouter than, the filiform proximal moiety of the rostrum, and are 

 suddenly expanded at their articular ends, each somite presenting 

 the appearance of a cylinder with a greatly truncated cone affixed by 

 its truncated surface to each end. The fourth and last somite is 

 scarce half the length of those that precede it, and is similarly ex- 

 panded at its anterior end only. From the sides of the expansions 

 at the posterior extremity of the second and third spring two some- 

 what inflated outwardly directed obconic processes, which might at 

 first sight be mistaken for the first of the basal joints of the legs 

 from their close similarity to these, but which are in reality one with 

 the somite from which they arise ; precisely similar processes carry 

 the legs both of the first and of the last somite, in which, however, 

 they diverge like the arms of the letter Y. Wedged in between the 

 roots of these processes of the last somite and the posterior boundary 

 of its ventral arc lies a minute obtusely conical tubercle with a large 

 circular (anal) aperture at its extremity. This is the abdomen, a 

 very evident, though rudimentary, structure in most Pycnogonida, 

 and even biarticulate in one species (in Zetes hispidus, Kroyer) ; but 



* Op. tit. ()1. cxix. figs. -5 & 8. 



t Naturhist. Tidssk. 1844, pp. 108 & 1 16. 



