108 J. R- KiNAHAN on the Britannic Species of 



along their superior margins, squamulated, and haired. The fifth pair is 

 smooth. 



The external maxillipeds exceed the rostrum by their propodos and dac- 

 tylos. The ischium is longer than the carpus, which latter is but moderately 

 twisted. Owing to its size, the characters of these appendages can be readily 

 studied in this species ; their details are therefore given at some length. 



The fourth pair of limbs (mandibles), (Plate X. 4'), is six-jointed, the coxae 

 soldered to the somite, the basis and ischium connate, the latter dilated at its 

 distal extremity into a strong process, which is hollowed longitudinally, two- 

 ridged, and its cutting edge rounded. Springing from the outer side of this is 

 the continuation of the limb, which is three-jointed; the meros and carpus 

 somewhat cylindrical and stout; the propodos lanceolate, its upper margin cili- 

 ate: these are carried folded down within an interspace behind the dilated 

 lobe of the ischium. From the proximal extremity of the basis, which is bifid, 

 arises the styliform accessory process, and from the junction of the basis and 

 ischium a small rounded membranous scale. 



The fifth pair (first masillaj) (Plate X. 5) is made up of two distinct articu- 

 lations. The basal (basis) quadrilateral, flattened, membranous ; its external 

 distal angle truncate, and furnished with a calcified rounded process below for 

 articulation with ischium; its internal border fringed with long hairs. The 

 second articulation (ischium) is elongated, triangular, its inner distal edge, 

 which represents the base of the triangle, armed with sharp, short, chitinous 

 teeth, which are arranged in three rows. Behind these, on its superior sur- 

 face, is a raised ridge, which is densely ciliated. From its outer edge, near its 

 origin, arises a curved membranous appendage (.v). The coxa, which is very 

 small, is connate with the somite ; a raised minute ridge crosses the ischium 

 opposite the origin of the appendage, Avhich may by some be looked on as an 

 articulation; but to me it does not appear to be such. 



The sixth pair (second maxillae) (Plate X. 6) is the most complicated of 

 the mouth appendages. The coxa {ex) is of a quadrilateral shape, but very 

 imperfectly calcified ; from its margin arises a broadly-lobed respiratory plate 

 («), which nearly completely encircles it; this is unequally three-lobed; an 

 internal lobe, small, extending into the mouth, and from the upper margin of 

 which the other articulations of the limb take their origin ; a basal, triangular. 



