ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 451 



The author deals in detail with the characters of the appendages of 

 the grouj) just mentioned, as also with those that follow. Into these 

 elaborate accounts it is imj)ossible to follow him here, and only the 

 more important general points can be dealt with. 



The Jurassic genera JJdora and TJdorella are seen to belong to the 

 Eukyphotes by having the epimera of the second abdominal covering 

 those of the first abdominal somite ; to this group also belongs 

 Hefriga. 



Distinct as are the Loricata, they would appear to be not distantly 

 related to Homarus ; the possession by them of an internal appendage 

 on the abdominal feet of the adult female is, indeed, a point of differ- 

 ence, but, as this character is found in the Thysanopoda though not 

 in the Penasidae, and in the Eukyphotes though not in Homarus, as 

 well as in such Decapods as Axius, the author is of opinion that it is 

 an ancestral character, which reappears by way of atavism. The 

 young of this group are transparent, and would seem to be surface- 

 swimmers. The lateral parts of the carapace are, as in Phyllosoma, 

 separated from the dorsal by a crest ; but this crest is low. Archceo- 

 carahus BowerhanJci would apjoear to be a true Pcdinurus ; Cancrinus 

 to be intermediate between the Palinuridae and the Syllaridee ; its 

 curious multiarticulate flagellum to the external antennte is a speci- 

 ally transitional arrangement. The ancestral form of the group seems 

 to be represented by the Palinurellus lately described by Von Martens. 



The Thalassinidfe, if Axius may be taken as their type, certainly 

 pass through a natant-stage ; the young, altogether similar in most 

 points to the adult, having small functionless epipodites to their 

 thoracic appendages, and the abdominal appendages larger than in the 

 adult. 



Mr. Boas is unable to accept the division of the Anomala suggested 

 by Professor Claus, who, it will be remembered, proposed to place the 

 Paguridse and Galathaeidse with the Macrura, and the Hippidae and 

 Porcellanidae with the Brachyura. The Danish naturalist points out 

 and insists on the relations between Galathea and Porcellana ; indeed, 

 all the forms he includes under the Anomala have important characters 

 in common : the thoracic limbs, maxillipeds, maxillae and mandibles, 

 no less than their developmental history, unite them most closely ; 

 "if there exists a natural group, it is that of the Anomala." They 

 have many points of affinity with Axius, although not directly derived 

 from it. 



The Brachyurous Dromiace^e have numerous points of affinity to 

 the Anomala, but their ancestor must have been more closely allied 

 to Axius. 



When we make a general survey of the results obtained by the 

 author, we find that from semi-transparent forms, delicate, and 

 actively swimming (Natantia), we pass to forms with a thick test, ill- 

 adapted for swimming, but able, thanks to their powerful abdomen, to 

 make leaps of considerable length (Homaridse). Thence wc are led to 

 the most highly differentiated Decapods, the Brachyura, in which, hand 

 in hand with the reduction of the abdomen, there has been a marked 

 increase in the development of the thoracic aj)pendages ; creatures well 



