BY DAVID G. STEAD. 749 



(3) Second .Ifaxilla (Fig. 1, D). This has the same flattened 

 leaf-like character as the one preceding, but differs considerably, 

 and is more interesting to us, inasmuch as the epipoditic portion 

 forms the Scaphognathite (Fig. 1, D, Sc). On the upper and 

 lower borders it is fringed with fine rather short hairs; these, I 

 lielieve, are modified forms of the hairs on the epipoditic portions 

 of the thi'ee maxillipedes, which I will presentl}'' describe. 



(4) First MaxiUipede (Fig. 1, C). This and the two following 

 appendages may really be divided into two portions, viz., the 

 maxillipede proper and the epipoditic portion, having two distinct 

 functions to fulfil. AVhen we compare this appendage with the 

 preceding we notice that a great change has taken place. The 

 exopodite {ex.) which in the second maxilla is very small, almost 

 spine-like, becomes here greatly developed. The description given 

 further on of the exopodite of the third maxillipede may also be 

 applied to this case, excepting that in this appendage the exopo- 

 dite is relatively larger than that of either the second or third 

 maxillipedes, and the long undivided portion is devoid of setai. 

 The remaining joints of the maxillijDede pi'oper are transformed 

 into broad thin plates, edged with setas. The epipodite consists 

 of a rather broad, thin, membranous lamella, gradually narrowing 

 towards its apex, and supported throughout its entire length by 

 a central calcified shaft. This lamella is fringed with fine hairs, 

 described further on. Just as in the second maxilla, where the 

 epipodite has been greatly modified to form the scaphognathite, 

 so, in the three maxillipedes, the epipodite has been considerably 

 metamorphosed to render it subservient to a special function, 

 which, in this case, is that of keeping the branchial chamber and 

 the branchiae themselves free from particles of dirt and. other 

 impurities, and to prevent the lodgment of parasites. Judging 

 l)y the amount of dirt to be found on certain parts of the walls 

 of the branchial chambers, the gills would soon become clogged 

 were it not for the constant action of these scrapers (for such they 

 are) moving over their internal and external surfaces. Viewing 

 them macroscopically, it would not perhaps be at once evident 

 how these scrapers effect their work, but when we subject them 



