THE GENUS ERETMOCARIS 363 



LARVAE FROM THE GREAT BARRIER REEF 



The Barrier Reef material examined includes 157 specimens of Eretmocaris, which 

 appears to be very common in these waters. No stages earlier than stages 4 or 5 have 

 been seen, although I have searched a number of the plankton samples for younger 

 specimens. The material is, on the whole, very well preserved, but leg 5 is generally 

 lost, only eighteen specimens having retained one or both of these legs. 



Three distinct species can be separated by easily observed characters, and the following 

 numbers show the relative frequency : 



Species i Species 2 Species 3 



132 15 10 



It may well be that two species are included in "species i ", separable by small details 

 in rostrum, length of eyes and antennule ; but I have not attempted a revision of the 

 material to determine this point. As none of the species can be named it seems sufficient 

 to establish the more marked types which can be easily recognized. All seem to belong 

 to one genus, and that probably is Lysmata. 



Two species, Eretmocaris remipes Bate and E. longicaulis Bate have been described 

 from the neighbourhood of Japan, but neither of these can be identified with any of the 

 Barrier Reef species. 



I give below short descriptions of the oldest specimens of each form. 



Species B.R. I (Figs. 29, 30) 

 Length less than 8 mm. 



Rostrum very short, with one dorsal spine. 



Carapace with median dorsal spine, and antennal and pterygostomial spines; supra- 

 orbital spines small or absent. There is a deep transverse groove in the gastric region 

 and lines as described above. 



Eye about as long as stalk, together less than one-third length of body. 



Telson about three times as long as wide, with two pairs of lateral spines and 5+5 

 terminal spines of which the second is the longest. No anal spine. 



Peduncle of antennule nearly one-third length of body. 



Leg 5 ischium and merus when distinguishable about equal, together twice length of 

 carpus; propod about i\ times length of carpus and 5! times longer than wide. 



Species B.R. II (Figs. 31-35) 

 Length up to 7 mm. 



Rostrum long and slender, with three dorsal spines. 



Carapace with median dorsal spine large and forming a procurved hook ; antennal and 

 pterygostomial spines present, but no supra-orbital. Carapace not deeply grooved, and 

 lines not traceable. Telson a little more than three times as long as wide, without lateral 

 spines and with 5+5 terminal spines of which 2 and 4 are the longest. 



