492 Scientific Intelligence. 



eighteen segments, divided into two regions. The anterior por- 

 tion consists of six segments, which with their appendages are 

 specialized for locomotion and prehension. The posterior region 

 of twelve segments is a vegetative sac. It is shown that the first 

 fusion of segments involved the three anterior ones. In the 

 Arachnids, the first segment was distorted and prolonged dorsally 

 for the purpose of developing the first pair of appendages as 

 powerful prehensile organs; while in the Merostomata, the 

 primitive differentiation occurred through a backward ventral 

 distortion and bending of the first segment. 



Considering the mouth as primarily anterior, its ventral position 

 in the Crustacea is the result of modification. Galeodes with its 

 anterior mouth is in this respect the most primitive Arachnid, 

 and to develop this type from Limalus, the latter " would have 

 to recover its long-lost Annelidan segments almost in their primi- 

 tive condition, and then, after tilting the first back *on to the 

 dorsal surface, further develop this primitive Arachnidan special- 

 ization till it reached the Scorpion stage. So that an animal 

 having carried one specialization to an extreme would have to 

 undo it all, in order to try a specialization the exact opposite of 

 its own. I think it fairly safe to say that this is impossible." 



A similar reversion and secondary progression would be 

 required to develop the Arachnid sternites out of a Limuloid, or 

 to produce the Arachnid abdomen from the specialized region in 

 JEurypterus or Limulus. Furthur conclusions of a like nature 

 are drawn from the construction of the beak out of a labrum and 

 labium; from the ocular tubercle, which is unknown in other 

 Arthropods; from the vestigial abdominal limbs, the nervous 

 system, the oesophagus, etc. " They separate the Arachnids 

 completely from all other Arthropods, and furthest of all from 

 Limulus, whose essential morphology, or, in other words, whose 

 early differentiation of the primitive ancestral metamerism was 

 the very reverse of that in the Arachnids. As Anthropods, no 

 relation whatever exists between them ; as segmented animals 

 however, they are both derivatives from the Chaetopod Annelids, 

 but along different and opposite lines of specialization." c. e. b, 



9. The Characece of America ; by Dr. T. F. Allen. — The third 

 fascicle of Part II of Dr. Allen's monograph has just appeared 

 and contains descriptions of ten species of Nitella with nine plates. 

 The new species are JV. Leibergii from Oregon, and A 7 ", transilis, 

 founded on JV. tenuissima var. longi folia ol Allen's Char. Exsic. 

 Amer. There is also a full description and figure of the little 

 known JV. Asagrmana Schaffner irom Mexico, and critical notes 

 on several varieties of JV. mucronata, JV. capitellata^ JV. gracilis 

 and JV. tenuissima. w. g. f. 



10. Kr yptog amen- Flora von Deutschland^ Oesterreich und der 

 Schweiz. Hysteriaceoe, Discomycetes (Pezizacese) ; by Dr. H. 

 Rehm. — This large volume of more than 1,200 pages, with many 

 figures illustrating the structure of the different genera, is one of 

 the best of the excellent monographs which, taken collectively, 



