'6(jS THE VOYAGE OF H.M.S. CHALLENGER. 



are crammed with minute eggs (<5V), which press on the genital bursas 

 (S,S) ; the strongly corrugated digestive cavity (St), whose upper wall 

 clings to the roof of the disk ; inter-mouth frame muscle (fm) ; jaw (c). 

 Fig. 5 OpMocamax, sp. nov. $ , -f-. [Exp. of U. S. str. " Blake."] Vertical section of 

 the disk passing through the sides of two arms. On either side is a genital 

 bursa (S,S) emptying by the genital opening (no), and making a fold 

 above over the digestive cavity (St), into which hang two more folds 

 (S,§) which are cut through. Above the bursas are pockets (S',8') 

 containing embryos just beginning to develop. A larger view of one of 

 these is given in fig. 4, Plate XLVI. ; section of second mouth-tentacle (r") ; 

 wings of arm bones shaved by the section (w'). 



PLATE XLVIII. 



Gorgonocephalus verrucosus, Lym. Diagram of the right stem, or half of an arm 

 carried out to its last forks, |. 



The figures indicate the order of forks as counted from the disk. Fork 1 is not seen, 

 as it lies within and under the disk, just beyond whose margin is fork 2 of this right 

 stem. 



For observations on the mode of forking among Astrophytons, see Proceedings of the 

 Boston Society of Natural History, vol. xix., March 7, 1877. 



This plate is quite a monument of patience on the part of my assistant, Miss Clark. 

 It is no fancy sketch, but a reduction of a large drawing, to make which every fine twig 

 was separately unrolled and measured, so that not only is the number of forkings correct, 

 but also the proportions of the parts. 



I take this opportunity to acknowledge the skill and fidelity of my artists, Miss K. 

 Peirson and Mr. L. Trouvelot, shown in the preparation of the original drawings and 

 the plates. 



