294 DISCOVERY REPORTS 



that descriptions of the adult are so often inadequate in substance if not in length, and 

 many pages of painful detail may contain no reference to the gill formula which is of 

 such fundamental importance. For example, the two genera Laomedia and CalHamdea 

 have been known for about a century, but I have found no full statement of the gill 

 formula of either. When one's efforts to find the systematic position of a larva fail, it is 

 some comfort to discover that the highest authorities on the systematics of the aduhs 

 are sometimes equally at a loss. For instance, Metaxius Bouvier, which may be a 

 synonym of Meticonaxins De Man, was referred to the Axiidae by De Man in 1925 

 and to the Callianassidae in 1928, while Callianassa coeca Balss is regarded by De Man 

 as a synonym of Meticonaxiiis monodon De Man.^ 



I have thought it well to include in this report two remarkable forms which may be 

 said to contribute evidence of the relationship of Axiidae to Nephropsidea. One 

 of them is referred provisionally to Nephrops, while the other is a post-larval stage of 

 Enoplometopus, a genus which is now regarded as an Axiid, but has previously been 

 included in the Nephropsidae. 



NEPHROPSIDEA 



Nephrops sp.? (Figs. 1-2) 

 Barrier Reef St. 7. 

 Length 4-8 mm. 



Rostrum long, triangular in section, with ventral ridge and lateral margins serrated. 

 Carapace with dorsal ridge in front, pointed anterior angle, but no other spines. Ab- 



Fig. I. Nephrops sp. ? 



dominal somites 2-5 without dorsal spines, but with sharply pointed pleural spines. 

 Somite 6 not separated from telson, longer than rest of abdomen. Telson triangular, 



^ According to De Man (1928, p. 30) Metaxius has epipods on legs 1-4, and he includes it in his new 

 subfamily Callianideinae. 



