48 DR. G. C. BOUKNE ON THE EANINIDJE : 
the external articular processes of the ni.indibles. There can he little doubt 
that these are the epiniera of the mandibular segment, and that they are 
homologous withi the less sharply defined areas similarly identified in the 
Astacura. 
In ^thtsa ciUatifrons the arrangements are Yery similar to those in 
^thusina, but the individual sclerites are not so easily distinguished. In 
this species the spout-shaped anterior end of the antennary sternum is pro- 
duced so far forwards that very little of the antennulary sternum can be 
seen in a surface -view. The mandibles also are reduced in size and the 
mandibular sternum is membranous. In Dorippe lanata the spout-like 
anterior end of the antennary sternum is produced forward to such an extent 
that it articulates with and ovei'laps the downward process of the rostrum, 
tlius completely concealing the antennulary slernum. This is one of the 
rare instances in which union is effected between the rostral process and 
the antennary sternum. In Doripp)e as in ^tlntsa the mandibular sternum 
is almost whollr membranous, exhibiting only two small calcifications in the 
reoion of the strophidia. The mandibular cpimera fre large and distinct, 
triangular in shape, the apices of the triangle produced backivards. The 
body of the antennary sternum exhibits a large central boss in front of the 
mandibular sternum, which might, at first sight, be taken for a forward 
median extension of the latter, but it obviously has no connection with it. 
After this survey of one of the families of the Oxystomatous crabs, the 
Eaninidse may be brought into comparison. Fig. 22 is a front view of 
the present region of Notopus dorsipes, all the appendages being removed 
with the exception of the right mandible and the left ocular peduncle. 
Fig. 23 is a similar view of Hanina dentata, and figs. 24 and 25 illustrate the 
same reoions in Notoscelex and Lyreidus. For descriptive purposes INotopus^ 
a less modified genus than Ranina or Lyreidus^ will be taken as the example 
of the family. The first thing to be observed is that the antennary sockets 
are relatively large and situated behind rather than to the sides of the 
antennulary sockets. In this respect Notopus more nearly resembles 
Homarus than Xeplirops, for in the latter the antennary sockets are dis- 
placed laterally. Reference to fig. 29 shows that in Notopus, as in all 
RauinidEC, the antennary peduncle is nve-jointed, the basal joint being freely 
moveable, short antero-posteriorly but of relatively considerable width ven- 
trally, and it bears the excretory aperture on a distinct prominent tubercle. 
In Notopus and in lianilia, M. Edw., the antennary flagellum is multi- 
articulate and of considerable length, with special features which will be 
referred to later. All these characters are Macruran. The antennules 
(fio-, 28) with their enlarged basal segmei.ts and abbreviated few-jointed 
external and internal flagella are more cancroid in character, but the basal 
joints are not inflated to anything like the same extent as in the Dorippidaj 
