754 



AUSTRALIAN CRUSTACEAN FAUNA, 



exceedingly numerous, average after extrusion ^mm. in length, 

 and •35mm. in breadth, and are of a yellowish colour. 



Fig. 3 — Neptunus pelac/iciis. 



A, First Pleopod of Female ; B, First Pleopod of Sterile Female ; 

 C and D, First and Second Pleopoda (copulatory organs) of Male. 



Ex. Exopodite ; En. Endopodite. 



The exopodite consists of one long joint (Fig. 3, A, ex.), and is 

 clothed (on the edges only) with fine plumose setae of a sensory 

 nature, from one-eighth to one-fourth of an inch in length. To 

 these hairs none of the ova are directly attached; they serve more 

 to keep the whole mass together. The first pleopod (that figured) 

 is the largest, and may be taken as a type of the rest, the only 

 difference of any importance being that the exopodite becomes 

 more lamellate in the three succeeding pleopoda. 



The next type of pleon that we have to consider is — as will be seen 

 by my diagrams — intermediate in formation, between male and 

 female. In this form (Fig. 2, B) the pleon only consists of three 

 movable segments, the 2nd, 3rd, 4th and 5th normal segments having 

 coalesced, though the sutures — denoted in the diagram as before 

 by the dotted lines — niay be at once observed. The telson, like 

 that of the male, is fringed with fine, short hairs. A noticeable 

 feature in connection with this form is, that the pleon is 

 not capable of extension to anywhere near the same degree 

 as that of the male or female, so that, even if the orifices 

 of the oviducts were large enough to admit of the passage of 



