Mr. C. Spence Bate on Synaxes. 225 



animal. The first joints are completely fused together and 

 with the somites to which they are attached ; and there is 

 nothing to distinguish them from the metopus or frontal sur- 

 face of the anterior somites, except the presence of the phy- 

 macerite, or tubercular opening to the green gland. Three 

 are all that are apparent as freely articulating joints belonging 

 to the peduncle of this pair of antennee. The terminal joint 

 that in the Scyllaridae exists as a broad, flat, and scale-like 

 plate, homologizes with the long multiarticulate flagellum of 

 the same antennae in Palinuridaj. 



The oral organs in the separate families are very distinct ; 

 but the individuality lessens in the appendages as they recede 

 from the mouth. The gnathopoda are in several of the 

 genera only specifically distinct. The pereiopoda or walking- 

 legs are typically the same even to the development of a 

 small chela at the extremity of the last pair in the females. 



The carapace is bolted down by a strong tubercle attached 

 to the sides of the last somite of the pereion {pereiocleis'^) , both 

 in the Palinuridge and the Scyllaridte ; and in each there is a 

 small aliform process that overlaps the posterior margin of the 

 carapace {pleocleis f) attached to the first somite of the pleon, 

 but which is less important in the Palinuridge than in the 

 Scyllarid«. All the somites of the pleon, inclusive of the 

 telson, are generically alike ; but the pleopoda or appendages 

 vary. 



In the Palinuridas the first pair is absent, and all the others, 

 except that which goes to form the tail-fan, consist of a single 

 round and foliaceous plate in the male, whereas in the female 

 the second pair (Plate XIV. fig. 6, q) has two foliaceous, 

 ovate, disk-like plates, the inner being attached to a two- 

 jointed pedicle ; the third pair (/•) consists of an inner three- 

 jointed biramose branch, and an outer, ovate, foliaceous 

 plate ; the two following are on the type of the third pair. 

 In the Scyllaridffi the first is present in both male and female, 

 and is biramose, but foliaceous in the female and styliforra in 

 the male (fig. 5, p). The four succeeding are biramose, one 

 branch being cylindrical and three-jointed, the other single- 

 jointed and foliaceous, being varied a little in both sexes; 

 but the whole are distinguishable from those of the Pali- 

 nuridge. 



The species which I have just described under the name of 

 Synaxes hyhridica appears to be a combination of the two 

 families — an intermediate form that connects the two very 

 dissimilar groups, and shows the way in which they approxi- 

 mate the more normal types of the Macrura. 



* (cXels, bolt, and pereion. t K\f\s, bolt, and pleon. 



Ann. &Mag. N. Hist. Ser. 5. Vol. vii. 17 



