THE G-NATHIIDJE 337 



When the young are ready to escape, the cuticle of the 

 mother, previously separated from the hypodermis, splits 

 into scales on the various segments. 



In the young the mouth-organs project beyond the 

 head, and are evidently formed for piercing and for suction ; 

 the mandibles have stiliform ends, and are followed by 

 two pairs of slender organs, which are considered to be 

 the two pairs of maxillas ; the maxillipeds are also slender 

 and elongate ; and the first gnathopods are elongate, 

 limb-like, with the normal seven segments; the first 

 perason-segment is distinct, the fourth, fifth, and sixth 

 being perhaps fused in the young female and distinct in 

 the young male. Dr. Dohrn considers it inappropriate 

 to speak of the mandibles as without ' palp ; ' rather, he 

 says, it is only the ' palp ' which appears to be present. 



It is said to be easy to keep the males alive for a year 

 or two in a small bowl containing some of their native mud 

 and some sea-water. As they are active climbers, pre- 

 cautions must be taken against their escape. 



Gnathia, Leach, 1814, has long been the only genus 

 contained in the family, to which it is entitled to give its 

 name, as hinted by Bate and Westwood, and properly 

 decided by the late Mr. Oscar Harger. For a long time 

 the name Anceus, Risso, 1816, was used for the males, and 

 Praniza, Latreille (Leach MS.), for the females and young. 

 M. Eugene Hesse has the credit of having definitely esta- 

 blished the relationship between the two forms, but it 

 should not be forgotten that Leach had expressed his con- 

 viction of it as long ago as 1814. The female had already 

 been figured and described as a marine Oniscus by Slabber 

 in 1769. The best known British species is Gnathia maxil- 

 laris (Montagu) 1804. The 'mandibles' of the male dis- 

 tinguish it from the species Gnathia Halidaii (Bate and 

 Westwood), instituted by those authors in 1866 with an 

 expression of some doubt as to whether it might not be 

 the same as Gnathia formica (Hesse). The American 

 species, Gnathia cerina (Stimpson) may likewise be dis- 

 tinguished by the ' mandibles.' M. Hesse has described 

 seventeen species from the coast of France, and given draw- 



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