bar iFii'. 15 i^^ coramencinj," from the outside, iha: is to 

 s.w, from the ed.ge turned towards the atri.ii cavity, we 

 have first a patch of columnar atrial epithelium, at the cor- 

 ners of which some of the cells contain a quantitv of the 

 rich brown pigment which has been referred to above as 

 being characteristic of the atria,: epitheliuni generallv. 



Fig. 15, A and i^. — Transverse seci^^ci •irongh priiciTy i. 



(-■S'l giT-h.3re. (Ar.er Besham. -'iig-niT itered.) 



j~r. Aniii epiihejnm. ^.f. Br:inchi,i] epnxhe'min. .". C.'^.>n^.:.' sp-i^^e c*" - 

 baj. .If, Ske>Txl r^ds. r. CotcmiL- res^e] o! pnnjan- bir. : . E\:e — i 

 of b,^:'"i toj^ r ". Ir^iemal vesse' of bo:h Kirf. 



N.B. — Benham r.o:d5 the ?raof i: the ir.-er eife c: :;:r skele:^' 

 t:*nct!e-b2j for ,i b-ood-resse'^ 



C 



d 5ecor:dajT 



u Uo:itedi 



, After ]_\N\~,rK;-iANi/i 



Next comes a ca\dtv which is a portion of the coflom, and 

 jS lined bv the iiat co?:omic epithelium. In fact, the dor- 

 sal, or subchorclal ccelom on each side icf. Fig. 2' is put 

 in connection vriih the endostvlar ccelom b\" a caj-salicular 

 detachment o: the cctlom which accompanies each primar\" 



