2-J TAOE .SKOGSliKl;i; 



foxali". Tlio I'XojKHlite iiiul the ciuloiHalitt' of the liiraiimus limb aiv in most cast's divided 

 into a larijor or smaller numbor i)f joints, wliich are usually distinct. 



ThethirdtviH\ the rod-shapt'clliinb. is iisually well j()iiitcd and o()nsists() Fa single n)\v()fj()iiits. 



The chief function of the foliaceous limb seems to be that of locomotion, swimming, and 

 its secondary functions are those of respiration, carrying the food to the mouth, breaking uj) 

 the food, etc. In the biramous limb these functions are differentiated and localized; the exo- 

 podite and endopodite are specially adapted for locomotion and the epipodial appendages 

 especially are used in respiration; the endites on some of the, limbs situated nearest the uKJuth 

 are differentiated for the function of taking up food. Tlie rod-shaped limbs are especially 

 locomt»tory t)rgans, functioning chiefly as organs for crawling and climbing. 

 hick v/ iltese types Which of these three types is to be considered as the most primitive? This seems an 



emo>iprimiiive. exceedingly difficult question to answer. 



It is rather common nowadays to consider, with Ray LaNKESTER, the first type, the 

 lobed foliaceous limb as most primitive (e. g. W. GIBSBRECUT in his comprehensive work on 

 the Crustacea, 1913). It is this type that we find in the P h y 1 1 o p o d s, the group that is 

 now generally and presumably correctly considered as the most primitive of all the recent 

 Crustacea known at present. 



Another view is maintained by C. Claus. This eminent investigator of Crustacea writes 

 }is follows in his important work of 1876, p. 17: ..Demnach wUrden wir zu dem gewiB nicht un- 

 berechtigten Schlusse gefiihrt, daB die Extremitaten der Stammkrebse, iiber deren Bau uns 

 leider die iiltesten palaontologischen Crustaceenreste zur Zeit keine Auskunft geben, keines- 

 wegs echte blattformige PhvUopodenfuBe waren, sondern den GliedmaBen von N a u p 1 i u s 

 ahnlich, eine Annaherung an die SpaltfilBe zeigten, welche nun um so leichter in einseitiger 

 Streckung der Aeste, den sich nach einer anderen Richtung mehr flachenhaft gestalteten Phyllo- 

 podenfiiBen gegeniiber, ihre Eigenthiimlichkeiten ausbilden konnten." According to this author 

 (p. 16) the epipodial appendages are later acquisitions. 



E. KORSCHELT and K. Heider seek the original type of the limbs of the Crustacea in 

 the bifurcated parapodium of the Annelids. In their textbook of 1890, p. 389 these authors 

 write as follows: ,,Man ist versucht, die typische zweiastige Form des Crustaceenbeines direct 

 von der ahnlichen gegabelten Gestalt der Annelidenparapodien herzuleiten. Hierfiir spricht 

 die eben erwahnte Thatsache, daB die Sonderung von Exopodit unci Endopodit sich an den 

 Beinanlagen von Branchipus ungemein friihzeitig geltend macht." The endites are according 

 to these authors new acquisitions; the epipodial appendages, on the other hand, are primitive 

 organs, which „man wohl mit einiger Wahrscheinlichkeit auf Dorsalcirren der Annelid en 

 beziehen diirfen". ,,Gegen letztere Auffassung spricht allerdings das verspatete Auftreten 

 "dieser Bildungen in der Ontogenie der Crustaceen. Doch darf man nicht vergessen, daB 

 eine Steigerung des respiratorischen Bediirfnisses erst bei einer gewissen KorpergroBe sich 

 geltend zu machen pflegt und es somit erklarlich scheint, wenn kleine Krebslarven (ebenso 

 wie ausgebildete Formen von geringer Korperentwicklung) der Kiemenanhange entbehren." 



J. Thiele also starts out fi-om the idea that the parapodium of the Annelids 

 is the original tvpe of the Crustacean post-oral limbs. This author writes, 1905, p. -467: 



