718 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Pmtanymphon (which were also found), and belongs to the family 

 Pycnogonidse. Unlike the ' Scotia ' and the ' Discovery,' the ' Pourquoi- 

 Pas ? ' obtained a true Pycnogonid, Pycnogonum garni sp.n. Bouvier 

 points out that the decapod types are primitive, that Decolopoda leads 

 on to Colossendeis, Pentanymphon to Nymphon, and Pentapycnon to 

 Pycnogonum. It is interesting to find all the three primitive types in 

 the Antarctic Seas, and perhaps there is still to be found the decapod 

 form of the Ascorhynchomorphs of Pocock. 



Olenellus and other Mesonacidse.* — Charles D. Walcott gives an 

 account of the development of the body in Mesonacid Trilobites, and 

 revises the classification. He adds several new genera — Nevadia, 

 Wanner ia, Psedeumias, and Peachella, and a number of species. He 

 discusses the abrupt appearance of the Mesonacidse, and the transition 

 to Paradoxinas. 



e , Crustacea. 



Dimorphism of Males in Saron.f — H. Coutiere corroborates the 

 conclusion of Borrodaile that Saron (or Hippolyte) marmoratus and 

 gibberosus are dimorphic males of one species. The form gibberosus 

 includes all the females and most of the males ; the males of the 

 marmoratus type are always very mature. 



Australian Amphipods.J — T. R. R. Stebbing reports on the ' Thetis ' 

 collection of Amphipods, which includes three new genera and thirteen 

 new species. The new genus Ochlesis is worthy of note, since by the 

 character of its maxillipedes it forms a Unk between the Gammaridea 

 and the Hyperiidea. For this reason it appears to justify the institu- 

 tion of a new family, the Ochlesidge. In all, forty-four species have 

 been identified among the specimens of the ' Thetis' collection. 



New Alpheidse.§ — J. G. De Man continues his report on the mac- 

 rurous Decopod Crustacea collected by the Siboga Expedition. He 

 describes 29 new species of Alpheidae, making a total of 113 species 

 (57 new). One new genus, Aretopsis, is established, in the immediate 

 vicinity of Arete. 



Rare Decapods. || — Mary J. Rathbun reports on a collection of 

 Decapod Crustaceans collected in Dutch East India and elsewhere by 

 Thomas Barbour. The collection includes the rare Thaumastocheles 

 zaleucus from deep water off Japan, in which the large chela is 108 mm. 

 in length, the whole body being 153 ' 5 mm. Other species little known 

 in collections are Utica nausithoe aud Macroplithalmus deftnitus. 



Commensalism of Sea-anemones and Hermit-crabs. IT— G. Brunelli 

 has experimented with Adamsia rondeletii and Pagurus arrosor, the 

 hermit-crab being deprived of its commensal and placed in an aquarium 

 with fixed and free Actinians. In detaching and attaching an Actinian 



* Smithsonian Misc. Coll., liii. No. 6 (1910) pp. 232-422 (22 pis.). 

 t Comptes Rendus, cl. (1910) pp. 1263-5. 



X Mem. Australian Museum, Sydney, iv. pt. 2 (1910) pp. 567-658 (14 pis.). 

 § Tijdschr. Nederland. Dierk. Ver., xi. (1910) pp. 287-319. 

 || Bull. Mus. Comp. Zool., lii. (1910) pp. 307-17 (6 pis.). 

 4 Atti Rend. R. Accad. Lincei Roma, 1910, pp. 77-82. 



