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species, N. latifrons, on juvenile characters, among which 

 a quite deviating shape of the frontal plate, it may be 

 useful to give a brief account of very young specimens. 



The Monaco collection contains a number of larval 

 specimens and of older stages with the thoracic legs almost 

 or fully developed, all belonging to N. Couchi Bell. In a 

 specimen with only three pairs of thoracic legs fully 

 developed the frontal plate is large, nearly quadrangular, 

 with the front margin transverve and slightly emarginate, 

 the carapace has a well developed denticle on its lateral 

 margin near the posterior end, the upper lobe on first 

 antennular joint is only a low protuberance, and the speci- 

 men is 4-5 mm. long. In a specimen, 5-8 mm. long, from 

 the same locality the frontal plate is proportionately a 

 little narrower in front, with the front margin itself feebly 

 convex with the angles rounded, the lower lateral margin 

 of the carapace has a low, protruding angle instead of the 

 denticle, the last pair of legs are nearly fully developed, 

 and the lobe on first antennular joint is more developed 

 than in the preceding stage. In a specimen, 6 mm. long, 

 from another locality the fifth pair of legs have scarcely 

 arrived at full length, an angle on the lower margin of the 

 carapace is indistinct, but the frontal plate agrees nearly 

 with Illig's fig. c, as it is much produced with the front 

 margin somewhat short but quite transverse, straight, not 

 emarginate. According to these facts I am sure that 

 N. latifrons Illig has been established on young specimens 

 of N. Couchi Bell ; Illig's largest specimen measured 

 8 mm. in length, his specimens were taken off West Africa 

 not far from Cape Blanco (I think at lat. 2i° N.) and I have 

 seen specimens of N. Couchi from the Atlantic coast of 

 Morocco. 



In young specimens measuring 6-7 mm. of N. simplex 

 n. sp. from the East Pacific the frontal plate is shaped 

 somewhat similar to that in the above-mentioned speci- 

 men of N. Couchi, but in the Pacific species the front 

 margin is even distinctly emarginate, and each angle 



