On the Bo(Jy-cavities cfcc. qftJie Actinotroclia. 09 



the last five joints bcin^ timcli contracted and furnished on 

 their inferior outer margins witli rows of short pectinate 

 spines. The fifth to seventh pairs are directed backwards 

 and increase in length posteriorly ; they have strongly curved 

 dactyla. 



Tlie uropoda are large, lamellar, and valve-like, folding 

 over and almost com|)letcIy covering the abdominal cavity ; 

 the posterior third is cut off by a transverse suture, forming a 

 separate j)late, which on its inner side bears a smaller fringed 

 plate; these two branches thus complete the valvular flaps. 



On opening out the uropods five pairs of pleopoda, each 

 with two well-developed oblong plates all closely folded over 

 one another, are displayed. The plates of the first two pairs 

 are thickly fringed with fine set£e on the margins ; those of 

 the last three pairs are simply branchial. 



Ilab. As already noted, this species has been obtained at 

 Stewart Island (no special locality or depth given), at 

 Tiraaru in 40 fathoms, and (presumably) at or near \Vanganui 

 in the North Island. 



EXPLANATION OF PLATE L 



Holognaihus S/eirarti, Filliol. 



Fiff. 1. Animal, dorsal view, nut. size. 



I'if/. tl. Ditto, lateral \iew, nat. size. 



J-'i)/. 3. luner auteuna. 



l'i(/. 4. Outer antenna. 



Fii/. 5. Upper lip. 



I'if/. 6. Lower lip. 



I'll/. 7. Left mandible. 



Fiff. 8. Right mandible, from inside. 



F^iy. 9. Ditto, from outside. 



Fig. 10. First maxilla. 



Fiff. IL Second maxilla. 



F'iff. 12. Maxillipeds. 



F)ff. 13. Uropod. 



XII. — Origin and Fate of the Body-cavities and the Nephridia 

 of the Actinotroclia. By R. P. Cowlks, Ph.D., Adam T. 

 Bruce Fellow in Zoology, Johns Hopkins University, 

 Baltimore, Md.* 



Since 1846, when J. Miiller discovered Actinotrocha brau' 

 chtatOy many investigators have turned their attention to the 

 anatomy and development of Phoronis ; but it is only within 



* From the 'Johns Hopkins University Circular,' April 1004, 

 pp. 2.S-37. 



