810 SUMMARY OF CUERENT RESEARCHES RELATING TO 



of the egg is now that of a T. 1 gives rise to 3 and 2 to 4 ; e and e' 

 then divide and give rise to m and m' ; the three germinal layers are 

 now formed. In the 12-stage there are four new ectodermic cells, 

 and in the 16-stage two more endodermie and two more mesodermic 

 cells. In the 24-stage there are eight new ectodermic cells ; the last 

 right and left are the two caudal cells of Goette. The blastosphere 

 has a small segmentation-cavity ; invagination commences in the 24- 

 stage. 



Development of Sphserularia bombi.* — Dr. E. Leuckart con- 

 firms the opinion of Schneider that the supposed female of S. homhi is 

 merely the protruded sexual apparatus of the female, and that the 

 latter is not, as was believed by Lubbock the male ; further observa- 

 tions, which are detailed, appear to show that the parasites make their 

 way into the bee at the commencement of its hibernation, and that 

 the fully-formed Sphserularia (female) is only found in the queen. 

 Copulation takes place during the free living stage of the worm. 



New Bothriocephalus.t— Prof. J. Leidy describes a new species 

 of BoiJirioceplialus or Dihothrium from a trout (Salvelinus sp. ?). The 

 worm is apparently different from either the D. infundibuUforme or 

 D. prohoscideum found in Salmo savelinus, S. solar, S. trutta, &c. Prof. 

 Leidy proposes to name it B. cestus. 



Circulatory and Nephridial Apparatus of the Nemertea.| — Mr. 

 A. C. Oudemans recognizes three types of vascular system in the 

 Nemertinea ; in the " palseo-type " there are two longitudinal blood- 

 spaces which communicate above the sheath of the proboscis, and are 

 lacunar in the cephalic and oesophageal regions ; in the tail they 

 communicate above the intestine ; the vessels in the tail of Carinella 

 form a loop above the intestine ; in Carinoma there are lacunar spaces 

 above the proctodoeum. Some forms have two other vessels in the 

 oesophageal region and in the sheath of the proboscis, but their con- 

 nections with the vascular system were only rarely made out. In the 

 " schizo-type," which not only obtains in the Schizonemertinea, but is 

 approached in the palaeonemertine families Valenciniidae and Poliidee, 

 there are, in the head, lacunar spaces which communicate both above 

 and below the proboscidian sheath ; there are, also, lacunar spaces in 

 the oesophageal region which coalesce on the ventral side ; in the 

 rest of the body we may distinguish three longitudinal, connected by 

 transverse vessels ; in the tail the communication is supra-intestinal. 

 The third or " hoplo-type " is distinguished by the possession of a 

 closed vascular system ; with the exception of Ampliiporus hastatm 

 the head contains two vessels which communicate in front, forming a 

 vascular loop above the proboscidian sheath ; these vessels also 

 communicate within the cerebral ring, but beneath it; from this 

 point down to the tail three longitudinal vessels occur, of which the 

 median vessel in the oesophageal region often lies partly in the pro- 

 boscidian sheath. The cephalic loop may form branches (e. g. Malacor 



* Zool. Anzeig., viii. (1885) pp. 273-7, 358. 



t Proc. Acad. Nat. Sci. Philad., 1885, pp. 122-3. 



X Quart. Journ. Micr. Sci.— Suppl., 1885, pp. 1-80 (3 pis.). 



