94 



K. KISHINOUYE. 



The ofenealoofica] tree which I would construct is as follows : 



Arachnida Merostomata 



Crustacea 



What order of 'i]\e Crustacea iy moA neai'ly related to tlie Gigant- 

 ostraca I do not know, sis the developmental liistory of different orders 

 of the class is not yet well known. 



I have already compared the eyes of Limuhis with those of the 

 Aracluiida, and foiuid that they are probahly hi^moh^u'ous witli each 

 other. ])iit I do not know whether the eyes of L'lmalm are homologous 

 with those of the Crustacea or not. 



The homology between the pulm(3nary sac of the Ai\aclinida and 

 the lamelligerous gills of Liinulns is most probable and is generally ac- 

 knowledged. l^>at as to the manner in which the former has been deriv- 

 ed from the latter, whether by invagination or by subsidence, o[)inions 

 of investigators do not agree. If a pulmonary sac of the Araclmida is 

 formed by the invagination of a lamelligerous appendage of a Lhnulu^- 

 like ancestor, (1) tlie mouth of the invagination ought to look towards 

 the head, (2) the gill lamellae ouglit to 1)8 formed on the posterior wall 

 of the invagination, (o) new lamellae ought tobe added ventral to those 

 already f ^rined, i.c.^ the most dorsal gill lamellae must be formed first. 



