330 DISCOVERY REPORTS 



Antenna: basis with small inner and outer spines; scale broad, without outer basal 

 seta. Mouth parts rudimentary. Endopods of maxillipedes 2 and 3 rudimentary, 

 seated low down on basis. Exopods on maxillipedes 



1-3 only. 



Chelaeoflegsiandalarge. Epipods absent. Four pairs 

 of pleopods, that of somite 2 very small. Uropods absent. 



UPOGEBIIDAE 



The development of the European species Upogebia 

 littoralis, U. stellata and U. deltaiira has been described 

 by Sars, Cano and Webb, and these species, though dis- 

 tinguishable as larvae, differ only in very small details. 

 The same is true also for larvae which I have attributed 

 to U. danai} Larvae which are easily recognizable as 

 belonging to the Upogebiidae are not uncommon in the 

 Discovery and Barrier Reef plankton, and the uniformity 

 of structure is very striking, having regard to the great 

 range of difference found in Axiid-Callianassid group. 

 There are, however, two forms of larva which require 

 description, the one because it departs to some extent 

 from the typical form and the other by reason of its 

 abbreviated metamorphosis. For convenience of com- 

 parison I include figures of the normal type of larva. 



Fig. 31. Thalassinid B.R. XI 



a. Telson. b. Maxillipede i. 



c. Maxillipedes 2 and 3. 



Upogebia sp. B.R. I (Fig. 32) 



Barrier Reef, St. 46. 



Stage III. Length 4-4 mm. 



General form as in U. deltaiira. Abdomen without spines ; pleura rounded. Telson 

 widening towards end, width about four-fifths of length; posterior margin slightly 

 concave, with very small median spine and a spine formula of 8, i, 8; spine 2 reduced 

 to a hair and spine 4 large, not jointed to telson. 



Antenna, basis with two small spines, exopod without outer seta near base, with 

 large apical spine ; endopod as long as exopod. 



Mandible without palp. Maxillule, palp of three segments, laciniae rather widely 

 separated. Maxilla with four large inner lobes; endopod unsegmented; exopod small, 

 with very small proximal process. Maxillipede i, endopod of five segments, with outer 

 setae on segments 1-3; inner setae strong and coarsely feathered. Maxillipede 2, 

 endopod of five segments, without outer setae on segments 1-4. Maxillipede 3, endopod 

 rudimentary, with long plumose seta near base. 



Legs large, with exopod on legs 1-3 ; leg i not chelate. Pleopods on somites 2-5. 

 Uropods, endopod without setae. 



1 Miss Hart's description of the larva of U . petgettensis (1937) was received after the paper was in proof. 



