286 CRUSTACEA. 



The third pair of maxillipedes is only present in a rudimentary 

 condition (Fig. 133 O). The next ontogenetic stage which develops 

 from the Zoaea (Fig. 133 /?), and which must be regarded as 

 equivalent to the Mysis stage of the Macrura, already shows all the 

 ambulatory limbs and the rudiments of most of the pleopoda. 

 The ambulatory limbs have no exopodites, and already approach 

 their final shape. We shall, in accordance with GLAUS (No. 7) and 

 in agreement with the similarly-shaped stage of the Brachyura, 

 define this stage as the Metazoaea. The characters of the Mysis 

 stage here seem suppressed. The Metazoaea must be regarded as a 

 transitionary form between the Zoaea and the youngest adult form 

 (Megalopa of the Brachyura). In one important point the Metazoaea 

 of the Anomura is distinguished from that of the Brachyura, viz., 

 the condition of the third maxillipede which here, though possessing 

 a rudimentary endopodite, has a well-developed exopodite functioning 

 as a swimming limb, while, in the Metazoaea of the Brachyura, this 

 limb still remains altogether rudimentary. This relation of the 

 third maxillipede to the locomotory function is a link connecting the 

 Anomura with the Caridea, in which the third maxillipede functions 

 as a locomotory organ as early as the Zoaea stage (p. 272). We 

 must consider this as a character of the Mysis stage precociously 

 developed, in which the Caridid Zoaea departs from the typical 

 Zoaea, while in the Metazoaea of the Anomura it must be regarded 

 as a last vestige of a lost Mysis stage. 



The development of the Anomura has recently been described in 

 detail by G. 0. SAES (No. 150), while fragmentary notices concerning 

 it were published earlier by GLAUS (Nos. 6, 7, 8, and 113), SPENCE 

 BATE (No. 98), DOHRN (No. 120), FAXON (No. 126), F. MULLER 

 (No. 140), SMITH (No. 152), and others. The development of 

 Eupagurus Bernhardus may serve as a type. 



The Zoaea of Eupagurus (Fig. 133 A] has a somewhat compressed 

 body, and is chiefly remarkable for the shape of its dorsal shield, 

 which runs out anteriorly into a long rostral spine, but is deeply 

 indented posteriorly, the indentation separating two points which 

 are directed backwards. A similar form of dorsal shield is found 

 in all Anomuran larvae. The short, stalked, and as yet immovable 

 paired eyes are remarkable for the posterior projections already 

 described in connection with Gebia (p. 284). Between them the 

 Nauplius eye can be recognised. The two anterior abdominal seg- 

 ments are covered by the dorsal shield, the sixth abdominal segment 

 is not yet marked off from the telson. The postero-dorsal margins 



