STUDIES IN AUSTRALIAN CRUSTACEA-McCULLOCH. 307 



or four below, those near the apex generally placed near one 

 another, so as to give it a bi- or tridentate appearance ; the 

 posterior two or three teeth are placed over the anterior part of 

 the carapace. The antennal and branchiostegal spines are well 

 developed, the latter being placed rather behind the vertical of 

 the other, but overlapping the anterior border of the carapace. 



Antennular peduncles not quite so long as the rostrum, their 

 flattened outer portions armed each with a terminal and median 

 spine. The two external flagella are united for ahout one-third 

 the length of the thickened flagellum, the outer margin of which 

 is obscurely serrated. The basal joint of the antennal peduncle 

 with a strong external spine; the flagellum about as long as the 

 entire body. 



The external maxillipeds extend a little beyond the antennal 

 peduncles, and their exopods are large and reach to the ends of 

 the ante-penultimate joints. 



The first pair of legs are very slender and reach a little beyond 

 the tip of the scaphocerite. The second pair are large and 

 cylindrical, and, when fully developed, extend almost as far as 

 the tip of the inner antennular flagellum. The merus do< s not 

 reach so far forward as the end of the scaphocerite. The carpus 

 is thickened distally, and is slightly longer than the palm, its 

 length varying a little with age. The palm is swollen and one- 

 third longer than the fingers. 



The three posterior pairs of legs are aubequal in length, slender, 

 cylindrical, and, with the exception of a row of minute spinules 

 on the lower border of the propodus, are unarmed. Short brushes 

 of setae overhang the bases of the dactyli, and there are scattered 

 bristles on the carpus and propodus of each leg. 



The telson terminates in an acute spine, on either side of which 

 is a long internal and short external one, both being movable. 

 Two pairs of spinules are placed on the hinder half of the upper 

 surface. 



Obs. — Miers 2 regarded L. serenus as a variety of L. intermedins, 

 but it is readily distinguished from that species by the branchi- 

 ostegal spine being placed on the margin of the carapace, and by 

 the different proportions of the carpus and propodus of the second 

 legs. 



There can be no doubt that the specimens from Port Jackson 

 determined by Spence Bate as Palumon affinis, M. Edw., are not 



2 Miers— Zool. Rep. "Alert," 18S4, p. 295. 



