Stiulirs on inarinr Ostrai'Oils 21 



tlio preceding literatuio. Fur several reasons the terms: iU'th, sixtli and seventh lunbs 

 seems to me most convenient; i. e. in the case of these organs one of the two methods 

 recommended by G. W. MtJLLER in his work of 1894 (cf. the ([notation on p. 1!» above) 

 has been adopted. 



P r e - o r a 1 limbs*: — 



First antenna: — With regard to this appendage I follow the terminology I'usi anicnnu. 

 used by G. W. MULLER in all essential points. On this appendage, as on all the following 

 ones, the joints are reckoned proximo-distally, unless something is said to the 

 contrary. In naming the different sides of the joints on this appendage, as on the 

 following ones, the appendage is always thought of in its natural position of rest, unless 

 something is said to the contrary. It is to be noted that the sides on which the joints border 

 on each other are always called the proximal and the distal sides; if attention is ])aid to 

 this, there is no danger of any mistakes. 



Post-oral limbs: — Pom-vral limbs. 



The post-oral limbs of the Crustacea may, as is known, be divided into three main 

 types according to their structure: the leaf-like or foliaceous, the biramous and the 

 rod -shaped limbs. 



The first tyjae is found in the Phyllopods and is characterized by W. GlESBRECllT A general duscniHK, 

 in his work of 1913, p. 31 as follows: The leaf-like limb consists of a lamella with an anterior "I ^'"^ '»«"";^''f" ' 



ihe posl-ural limbs t 



and a posterior surface and with medial, distal and lateral edges; the edges are provided with ihrCnu'Kiren. 

 hairs and bristles and have lobes and processes. Its middle jjiece is called the protopodite, 

 the lobes and processes are called exites, if they are situated on the lateral edge of tlie lamella, 

 endites, if they issue from its medial edge. In a number of forms the protopodite appears to 

 -be — though sometimes only rather incompletely — divided into transverse joints. The exites 

 and endites may sometimes not only be bounded from the protopodite but also divided more 

 or less distinctly into joints themselves. 



The second type of limbs is described by W. GlESBRECHT in his work just quoted as 

 follows: The biramous limb consists of a trunk, the protopodite and two branches, an outei- 

 one called the exopodite and an inner one called the endopodite. Proximally of the exopodite 

 and the endopodite exites and endites may occur on the protopodite; the former are called 

 epipodites. The protopodite of the biramous limb is proportionately less strongly developed 

 than in the foliaceous limb and is in most cases divided into two joints, the proximal one of 

 which is called the coxale, the distal one the basale. It is to be noted that in most cases probably 

 only the distal part of the protopodite (jf the leaf-like limb, the part that has the exites, is to 

 be considered as homologous to the protopodite of the biramous limb; that part of the proto- 

 podite of the latter type which corresponds to the proximal part (^f the protopodite of the 

 former type seems, in most cases, to have been more or less completely united to the body of 

 the animal. Sometimes, when this union is less complete, one can, however, observe a joint 

 or the remains of a joint between the coxale and the body; this joint is usually called the pro- 



• G. W. MiJLLEK ill his worlv uf 1894 considered Ijolli llie first and second aiiti-iiiuu- as pre-oial. Now, as is wi'll 

 liiiowii, tlic socoiid antennae of all Crustacea hiWi- bocii sliowii to l)e post-oral. 



