300 



Family Crangonidae. 



Aegeon (Risso) Guér.-Ménev. 

 Aegeon ])ennata (Bate), var. affinis Alcock. 



Syn. : Aegeon affine, A. Alcock, A descr. Catal. Indian Deep- 

 Sea Crustacea, Calcutta 1901, p. 118. 



Illustrations Zool, „Investig-ator", Plate LI, Figs. 3, 4. 



The examination of 7 typical specimens of A. pennata (Bate), 

 oollected by the „Siboga" in Lobetobi Strait and in Saleh Bay, 

 Sumbawa, proved that A. affinis Alcock from off Bombay should 

 be considered at least as a distinct local variety of Bate's species. 

 Among the 7 typical specimens are two full-grown females of 

 equal size, long 43 mm. from tip of rostrum to tip of telson, and 

 one adult male long 37 mm. When the cited figures of A. affinis 

 are indeed accurate and correct, the typical species differs by the 

 body being less hroad in proportion to the length : in fig. 3, 

 representing the female of A. affinis^ the body appears only fout' 

 times as long as the 2nd somite of the abdomen is wide, in the 

 full-grown typical females, however, five times, in the male of 

 the variety five^ in that of the typical form about six times. In 

 the typical species the posterior moiety of the lateral crest of 

 the carapace runs straight backward, parallel with its fellow, and 

 one observes usually only one minute notch just behind the spine 

 at the anterior extremity : in the variety affinis the posterior 

 moiety of this crest is coarselij serrate along its /vhole length. In 

 the adult male and in the adult female of the typical species the 

 antepenultimate thoracic sternum is smooth^ in the male the two 

 posterior sterna are sharply carinated in the middle line, in the 

 female also smooth ; in the variety affinis^ however, in the male 

 the last three thoracic sterna are sharplij carinated and in the 

 female the carination of the antepenultimate sternum is distinct^ 

 but that of the last two is obsolescent. 



h\ the typical species, finally, the 2nd peraeopods do not differ 

 in the two sexes, reaching both in the male and in the female 



