CHAEACTEEISTIC SPINES 281 



Family Squillidce. 



As this is now the only family, it has the characters of 

 the sub-order. The family Eiichthidee, which was formerly 

 its companion, has been shown to consist entirely of larval 

 forms. In the Squillidae Brooks accepts ' seven genera, Pro- 

 tosquilla, Gonodactylus, Pseudosquilla, Coronida, Lysiosquilla 

 (including Goronis), and Squilla (including Ghloridella).' 

 As only six genera are named, it is doubtful whether seven 

 is a misprint, or intended tacitly to include Leptosquilla, 

 Miers, which had been previously spoken of as very slightly 

 known. Professor Brooks lays great stress on the marginal 

 spines of the telson, of ivhich there are usually six, arranged 

 in three pairs. These he designates as the primary mar- 

 ginal spines, and distinguishes the tivo nearest the middle 

 line as the submedians, the two nearest the anterior edge, 

 which are usually the farthest from the middle line, as the 

 laterals, and the one between the lateral and the submedian 

 on each side as the intermediate; ' Between these six 

 primary marginal spines there are others which are equally 

 large and prominent in the young larvae, but minute or 

 absent in the adults ; ' these he calls the secondary mar- 

 ginal spines. The characters of the great second maxilli- 

 peds, spoken of as the raptorial claws, and the connection 

 of the sixth segment of the pleon with the telson, are also 

 of great importance in distinguishing the genera. Another 

 structure, which ' often presents characteristics of specific 

 value, and differs conspicuously in the different genera,' is 

 that found upon the inner branch of the first pleopods in 

 the male, ' a complicated grasping organ which probably 

 serves for seizing the female, like the grasping forceps of 

 many of the lower Crustacea and some few of the Mala- 

 costraca.' 



Sqvdla, Fabricius, 1793, agrees with all the other 

 genera, except Protosquilla (and perhaps Coronida), in 

 having the sixth pleon-segment separated from the telson 

 by a movable joint. The terminal joint of the second 

 maxillipeds is without a basal enlargement, but with a 

 series of spines, usually not more than six in number, on 



