ZOOLOGY AND BOTANY, MICEOSCOPY, ETC. 449 



take the form of rudimentary hermaphroditism ; that is to say, the 

 structural arrangements do not permit self-fertilization. 



Auditory Organ of the Ixodidse.*— Dr. G. Haller points out that 

 near the hinder margin of the terminal joint of the first pair of feet 

 of these animals there are two foramina, which are covered by a 

 colourless transjsarent membrane ; within this we find chitinous haii-s 

 and otoliths, which present an extraordinary resemblance to the audi- 

 tory arrangements of the Crustacea. The Ixodes of the dog afforded 

 the author an ample supply of material. 



5. Crustacea. 



Deep-sea Crustacea of the Gulf of Mexico, t — M. Alphonse Milne- 

 Edwards has a note on the forms, the names of which were given in 

 this Journal, ante, p. 240. Not only is the number of species much 

 greater than was expected, 53 out of 240 being new in the groups 

 already examined, but 40 are new generic types. Certain groups 

 which had been supposed to be absent from the American seas are 

 very richly represented at these great depths ; Galacantha has its 

 carapace armed above and laterally by large sabre-shaped spines ; 

 and OropJiorhynchiis can withdraw its eyes under its rostrum. 



Crabs proper — Brachyurous Decapods — disappear below 500 m. 

 from the surface ; at 800 m., however, there was found Batliyplax, 

 which takes the place of Gonoplax of the French coasts, but it is 

 blind. Representatives of Willemoesia were found at 3500 m., and 

 these too were blind. 



The infinite variety of the forms is, however, the most astonish- 

 ing point, and great difficulties are raised as to future classifications ; 

 transitional types abound, and groups hitherto regarded as very 

 distinct are now linked by intermediate forms. As examples, the 

 author cites the Paguridee, generally placed among the Anomura, and 

 which have as yet had no link uniting them to the Macrura ; now 

 there is PylocJieles Agassizii, in which the abdomen is not soft and 

 asymmetrical, but is formed of solid regular rings, and terminated by 

 swimmerets. This creature lives in holes, which it closes by means 

 of its claws. Mixtopagurus has the febdomen more developed on the 

 right than on the left side, and divided into seven somites, of which 

 the last two are alone large and hard. Catapagurus has a very small 

 abdomen and leads to Spiropagurus. 



There are some curious adaptive modifications : Eupagurus dis- 

 coidalis, which lives in the tubular shells of Dentalium, has one of its 

 claws spherical. Xylopagurus lives iji hales in wood, and has its 

 abdomen converted into an operculum for covering one of the two 

 holes of its retreat. 



Similar connections are found between the Dromiad^e and the 

 Homolidae ; and on the whole the author concludes that submarine 

 explorations will aid pal^ontological investigations in gradually 



* Zool. Anzeig., iv. (1881) pp. 165-7. 

 • t Comptes Kendus, xcii. (1881) pp. 384-8. 



