On a Group of the Aplysiidge. 403 



mandibles ; /./., lower lip ; mi\ 1, one of the first maxilke, and spines 

 of the outer plate of the other more highly magnified ; mxp., maxil- 

 lipeds; gn. 1, fir;st gnathopod; gn. 2, second gnathopod; prp. I, 3, 4,5, 

 first, third, fourth, and fifth peraeopods ; ur. 1, 2, 3, first, second, and 

 third uropods ; T, telson. 



The mouth-organs and parts of the pleon are much more highly magnitied 

 than the antennae and limbs. 



Plate XV. A. 



Deutella Mayeri. 



Lateral view of the female above, and of the male below, the natural 

 size of the male being indicated by a line on the right. 



OS., the mouth-organs of tbe male specimen viewed laterally in situ. The 

 palp of the mandible is seen overtopping the upper lip ; the lower 

 lip can be perceived almost edgewise below the molar tubercle of 

 the mandible and above the palp of the first maxilla ; between the 

 latter and the prominent palp of the maxilliped are discerned the 

 two plates of the second maxilla. 



l.i., lower lip ; mx. 1, first maxilla ; wi.r. 2, second maxilla ; mxp., maxilli- 

 peds ; gn. 1, first gnathopod. This group is taken from a specimen 

 smaller than either the male or female specimen figured on the plate. 



ft.s., upper antenna ; a.i., lower antenna ; gn. 1, first gnathopod ; g)i. 2, 

 second gnathopod; prp. I, 2, 3, 5, first, second, third, and fifth 

 peraeopods. 



The parts of the female are distinguished by the sign $ , of the male 

 by the sign c? . 



XLVII. — On a Group of the Aplysiidffi, with Description of 

 a new Species. By J. GiLCHRiST, Ph.D., &c. 



[Plate XVIII. ] 



The following description of a small group of Aplysias is a 

 contribution to an account of the collection of Tectibranclis 

 in the British Museum (Natural History). This collection 

 contains a great number and variety of forms from the 

 Pacific, Atlantic, and Indian Oceans, and illustrates very 

 forcibly what could be done if a systematic search for these 

 animals were made in almost any unexplored region. Owing 

 to careful preservation and a liberal supply of spirit some of 

 the specimens are in a good state of preservation and sufficient 

 for purposes of identification. 



The small group to be considered here is represented by 

 half a dozen specimens, more especially by Aplysia piperata 

 (Smith), from Thursday Island, Torres Straits (* Alert ' 



