138 A HISTOBY OF KECENT CEUSTACEA 



of feeding, motion, and generation, and in the fabric of the 

 trunk within. The vulvse are not in the trunk, but in the 

 bases of the third pair of legs. The sternum is deeply ex- 

 cised between the last pair of legs ; the turkish saddle l 

 and median apodeme are wanting ; the transverse septum 

 of the apodemes forms in the middle a central yoke and 

 central canal. Further, they show a peculiar affinity to 

 Homola by the eye-stalks, which are very long, thin, 

 apically inflated, as good as free, 2 by the first antennas not 

 retractile into fossettes, by the first and third maxillipeds, 

 which so agree in the two genera that they can. scarcely 

 be distinguished. With the Maiacea, therefore, LatreiUia 

 cannot be confounded, although the form of the trunk is 

 triangular, the legs are very slender, the epistome is qua- 

 drate, and of the branchias there are ten pairs, of which 

 three are connected with the maxillipeds, two with the 

 chelipeds, and three with the following legs, but the last 

 united with the penultimate legs.' 



Latreillopsis, Henderson, 1888, with a type species, 

 Lafreilloptiis bispinosa, from the Philippine Islands, ' occu- 

 pies an intermediate position between the genera Homola 

 and LatreiUia. From Homola it is distinguished by the 

 arrangement of the rostrum and supraorbital spines, the 

 greater length of the ocular peduncles, and more especially 

 by the elongated cylindrical legs. In LatreiUia, on the 

 other hand, the frontal region is narrow and produced so 

 as to give the carapace a triangular outline, the supra- 

 orbital spines are more strongly developed, and the eye- 

 stalks and legs are of greater length.' It may perhaps be 

 regarded as something more than a mere coincidence that 

 this link between Homola and LatreiUia was obtained by 

 the Challenger in one of the two localities in which the 

 same vessel took specimens of those two genera. 



Homologenus, A. Milne-Edwards, 1888, bears a name 

 altered from the pre-occupied Homolopsis, 1880. It differs 



1 The expression ' posterior turkish saddle,' is applied by Milne- 

 Edwards to the small arch formed by the sternal apodemes which 

 spring- from the hind margin of the last segment of the trunk. 



2 The Latin is totis quantis lileris. 



