BY WILLIAM A. HAS WELL, M.A., B.SO. 281 



It is in the structure of the antennae that this form shews its 

 parentage most unmistakeably. These organs, as in Ibacus and 

 the rest of the SeylJarina, have the first segment coalescent with 

 ^he sternum of the antennary somite ; on its ventral surface is 

 a perforated tubercle representing the so-called " green-gland " 

 of the adult ; the second segment is short and broad ; the third 

 has a basal part, of similar form to the second seg ment, and armed 

 internally with a strong, curved, pointed spine, and an external 

 expanded foliaceous portion, of oval pointed form, and armed 

 along its outer border with three small teeth ; the fourth segment 

 resembles the basal portion of the third, and has a similar spine 

 on its inner surface ; the terminal segment is phylloid, oval, 

 pointed, armed on its inner border with four strong, triangular, 

 pointed teeth and on its outer with a single obscure denticle. The 

 structure of the antennae in Ibacus is almost precisely similar to 

 this, save that the form of the phylloid expansions is somewhat 

 altered, and the number of teeth on them increased. 



The labrum is large and prominent. The mandibles are still 

 membranous. The first maxilla) have the exopodite rather longer 

 than the endopodite, and both armed with several setae, which 

 are longer on the latter. The second maxillae are large and 

 foliaceous ; the endopodite is a simple, blunt process, with a 

 crenated internal border ; the scaphognathite is large, the 

 exopodial portion which is slightly truncate anteriorly, is twice 

 as long as the endopodite ; the epipodial part is shorter than the 

 exopodite, broad and rounded. The first maxillipedes are 

 rudimentary consisting of a short process to which three 

 branchial (?) filaments are attached. The maxillipedes of the 

 second pair consist of four segments ; their extremity reaches the 

 front of the labrum ; the appendage on their second segment is 

 short. The third pair of maxillipedes, which have five articulations, 

 are about five times as long as the second ; their appendage is 

 about equal in length to that of the latter. 



