102 Records of the Indian Musenin. {Yoh. XII, 



are those made use of in my key to the Indian species {loc. cit., 

 p. 113): the rostrum is longer than in other species of the genus 

 and is provided with an elevated dentate basal crest ; the telson is 

 lanceolate, with the apex acute and unarmed. 



These characters appear to me to be altogether unsuitable for 

 generic definition and are clearly of far less morphological value 

 than those hitherto employed in the generic subdivision of the 

 family. In young spechnens of H. ensirostris there is a pair of 

 long spines at the tip of the telson, reaching far beyond the pro- 

 duced median point and these may still be seen in a reduced con- 

 dition, even in individuals 40 mm. in length. Stebbing also, when 

 describing Exhippolysmata tugelae, notes the presence of a very 

 small spine on either side of the telson tip. The claims of Exhip- 

 polysmata to generic rank rest therefore on the rostral characters 

 and in the fact that the telson has a median point instead of being 

 rounded. If it be retained, its recognition requires to be balanced 

 b}^ the institution of a considerable number of other " new genera," 

 a procedure which seems unlikely to serve any useful purpose, 

 while tending to confuse the natural afitinities of the component 

 species of the family. 



Lysmatella, recentl}'' instituted by Borradaile for a species 

 from the Maldives, is based on surer structural differences, but is 

 none the less very closely allied to Hippolysmata. In the very 

 brief preliminary diagnosis that Borradaile has given,' it is merely 

 described as " related to Lysmata, but without mastigobranchs on 

 the legs." The type species of the genus, Lysmatella prima, is 

 described in the same paper. 



Three specimens, recently obtained in the Andanians, agree 

 in every particular with the generic and specific descriptions that 

 Borradaile has given ; but, unfortunatel}^, the information is so 

 meagre that it is impossible to be certain of their identity. The 

 Andaman specimens are, however, clearly related in a ver^^ close 

 manner with the species of Hippolysmata belonging to the vittata 

 group, the afifinity being shown not only by the almost exact 

 correspondence in all structural details (except for the absence of 

 epipods), but also in colour, the specimens when alive exhibiting 

 the brilliant longitudinal red streaks that characterise H. vittata 

 and H. dentata. 



If my identification of the Andaman specimens is correct it 

 appears to me unwise, in the present state of our knowledge, to 

 recognise Lysmatella in full generic significance. The presence or 

 absence of epipods is in many cases a valuable aid to generic 

 diagnosis in the Hippolytidae, but the number of these structures 

 is variable in the genera Spirontocaris and Latreutes and in Hip- 

 polysmata ensirostris the entire series is rudimentary. In many 

 species referred to Hippolysmata the epipods have not been ex- 

 amined and, on analogy with other genera, it would occasion no 

 surprise if some were found to possess a reduced number. 



1 Borradaile, Ann. Mag. Nat. Hist., (8), XV, p. 206 (1915). 



