572 



SCIENCE. 



[Vol. II., No. 38. 



tory of the orders of Crustacea, the sub-onlers 

 of Branchiopocia, and the fumilies of Phyllo- 

 poda. It is said that this diagram " may also 

 serve as a genealogical tree, showing the prob- 

 able ongin of the main divisions of the Crus- 

 tacea :" but the genealogical part of thediagram 

 consists simply of dotted lines connecting the 

 points of first appearance in geological history 

 of the Branchipodidae, Apodidae, and Clado- 

 cera, with the point of appearance of the Lim- 

 nadiidae in the Silurian ; the common stem 

 from this point with the Ostracoda in the upper 

 Laureutian ; and the branchiopod stem thus 

 formed, and continued to a hypothetical Pro- 

 tonauplius in the lower Lauren tian, with the 

 points of appearance of the Malacostraca, 

 Phyllocarida, and Cirripedia. On what con- 

 ceivable theory of evolution this would repre- 

 sent a possible, much less the probable, origin 

 of the main divisions of the Crustacea, it is 

 hard to imagine, and was probably not serious- 

 l3- considered bj' the author himself; for it is 

 far less like a probable genealogical tree than 

 the diagram on p. 448, illustrating tlie rela- 

 tions of the Phyllocarida to other Crustacea. 



In the chapter on morphologj' and anatomy, 

 Professor Packard discusses at length the mor- 

 phology of the regions of the body and the 

 appendages of Arthropoda in general, and of 

 the crustacean limb in particular, and gives 

 some account of the anatomj- of the phyllo- 

 pods, but adds very little to our previous 

 knowledge of the anatomy of the group. The 

 morphological discussion is an interesting con- 

 tribution to the suliject, and, with the numerous 

 figures with which it is illustrated, will prove 

 very useful, although most of the new nomen- 

 clature proposed for the regions of the body 

 and appendages is very objectionable. Pro- 

 fessor Packard sa^'s, " For the primar3' regions 

 of the head {sic), the onl}- scientific terms as 

 3'et in use are those proposed by Prof. J. O. 

 Westwood, in Bate and Westwood's History 

 of Bi-itish sessile-eyed Crustacea (vol. i. p. 3). 

 These are cephcdon for the head, pereion for 

 the thorax, and pleon for the abdomen ; while 

 the thoracic feet are termed pereioporia, and the 

 abdominal legs pleopoda ; the three terminal 

 pairs being called uropoda. As the names 

 applied to the thorax and abdomen have no 

 especial morphological significance, the Greek 

 TTcpaioi', simply meaning ulterior, and TrAeoi', 

 more, we would suggest that the head be 

 termed the cephaloso-tne, the cephalic segments, 

 cephalomeres, and the cephalic appendages in 

 general, protopoda, the term 'cephalopoda' 

 being otherwise in use. The thorax of insects 

 and of most Crustacea might be designated the 



baenosome (/Jatra, to walk, locomotion), and 

 the thoracic ap|)endages, baenopoda, the seg- 

 ments being called bnenomeres ; while nrosome 

 might be applied to the abdomen, the abdomi- 

 nal segments being called uromeres. West- 

 wootl's term tiropoda might be extended so as 

 to include all the abdominal appendages." If 

 mere names of parts are to be rejected, simply 

 for want of ' morphological significance,' the 

 language of the morphologist would soon be- 

 come a meaningless jargon, to which it is near 

 enough already ; but, even as to ' morphological 

 significance,' there appears to be little choice 

 between the new and old terms. Bate, when 

 first jn'oposing the terms ' pereion' ' and ' pleon,' 

 expressly states that he derives the terms from 

 Trepatoo) {^ to loalk about') and ttAcw {navigo). 

 The proposed term ' protopoda ' is quite as un- 

 fortunate as ' cephalopoda,' since • protopodite ' 

 and ' protopod ' are alread}' in use for parts of 

 crustacean appendages, the former even in the 

 present work. The extension of the term 

 ' uropoda ' so as to make it synonymous with 

 ' pleopoda ' would also be unfortunate, since, as 

 now employed, it is a very useful term to des- 

 ignate the modified caudal pleopoda, whether 

 one, two, or three pairs. 



In the chapter on development, metamor- 

 phoses, and genealogy, Professor Packard 

 gives a short account of the nauplius form in 

 Phyllopoda as an introduction to Dr. (iissler's 

 interesting notes in the following chapter, and 

 then briefly discusses the phylogeuy of the 

 group, in which he appears to find but one dif- 

 ficulty. He says, — 



" The difficulty is (and this is a point ap- 

 parently' overlooked by Fritz Midler, Dohrn, 

 Claus, and Balfour) to account for the origina- 

 tion of the phjdlopods at all from any marine 

 forms. The only explanation we can suggest, 

 is that the phyllopods have arisen through 

 Limnelis directly from some orginally marine 

 cladocerous type like the marine forms now 

 existing, such as Evadue. We imagine that 

 when a permanent bod}' of fresh water became 

 established, as, for example, in perhaps early 

 Silurian times, the marine forms carried into 

 it iu the egg-conditiou, possibly bv birds or by 

 high winds, hatched young, which, under favor- 

 able conditions, changed into Sida, Moina, and 

 Daphuia-like forms." 



Professor Packard appears to have over- 

 looked the difficulty of the eggs of any marine 

 cladocerous type of animals surviving a sud- 

 den transfer from salt to fresh water, and the 



I According to L-ilhor Biitc'a or Pjicknrd's derivation, (his 

 would bu more propt-riy writlcn peraeun, us lias eomclimes been 

 done, or eveuperco«. 



