l»i-± SUMMARY OF CURRENT RESEARCHES RELATING TO 



of more or less cosmopolitan distribution, that occur in South America, 

 are not autochthonous there, but immigrants from the northern hemi- 

 sphere. -1. The autochthonous animals of South America have spread by 

 migrations through Central America to the south of the United States, 

 but in no single case beyond America to the palasarctic region. 



Monograph of West American Pyramidellidae.* — W. H. Dall and 

 P. Bartsch have executed a laborious task in this monograph of a family 

 of Gastropods, the members of which are mostly of minute size. The 

 distribution is world-wide. There are four main genera — Pyramidella 

 Lamarck, Twbonilla Risso, Odostomia Fleming, and Murchisonella Morch, 

 with a large number of sub-genera. 



5. Lamellibranchiata. 



Postembryonic Development of Unionidse.f — W. Harms begins by 

 giving a fresh description of the glochidia of Anodonta, Umo, and Mar- 

 garitana, and he also refers to the peculiar Lasidiiim-lnTvu of the South 

 American mussel, Glabaria, one of the Mutelidas, in which a parasitic- 

 stage has not been discovered. The transition to parasitism is then dis- 

 cussed, in connection with which it is noted that tadpoles, Proteus, and 

 axolotl may be infected, as well as fishes. Only in the axolotl, however, 

 does development complete itself. Harms then proceeds to the main 

 subject of his investigation, the changes that go on in the parasitic period, 

 leading to the definitive mussel form. 



Arthropoda. 



Muscle-insertions in Arthropods. J— R. H. Stamm discusses the in- 

 sertion of muscles in the chitinous skeleton of Arthropods, and defends 

 against other observers the conclusion which he arrived at in 1904, that 

 the insertion is always " indirect." The typical cross-striped muscle- 

 substance never reaches the chitin, but is always separated from it by a 

 longitudinally striated tendon, which is due to modified hypodermis cells. 



o. Insecta. 



Mouth-parts of Wasps and other Hymenoptera.§ — R. Deinoll gives 

 an account of the mouth-parts in Vespidaa, Tenthredinidae, and Uro- 

 ceridae, and describes what seems to be an olfactory organ at the end of 

 the labial palp of Sirex gigas. 



Brain of Hive-bee. || — C. N. Jonescu gives a detailed comparative 

 account of the complex brain of the hrVe-bee. The supra-cesophageal 

 ganglion has its protocerebrum (with several subdivisions), its deuto- 

 cerebrum, and its tritocerebrum ; the sub-oesophageal ganglion is triple. 

 The origin of the various nerves from the brain is described. Some of 

 the comparisons of the brains of queen, worker, and drone are very in- 

 teresting. The worker has, as is well known, a larger brain than the 

 queen. In the drone the optic lobes are large, corresponding to the large 



* U.S. Nat. Museum, Bull. 68 (1909) xii. and 258 pp. (30 pis.). 



t Zool. Jahrb., xxviii. (1909) pp. 325-86 (4 pis. and 9 figs.). 



% Anat. Anzeig., xxxiv. (1909) pp. 337-49 (7 figs.). 



§ Zeitschr. wiss Zool., xcii. (1909) pp. 187-209 (1 pi. and 9 figs.). 



|| Jenaische Zeitschr. Natur., xlv. (1909) pp. 111-80 (5 pis. and 13 figs.). 



