ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 637 



7. Myriopoda. 



Anatomy of Polyxenus lagurus.* — Mr. F. G. Heathcote gives a 

 description of some points in the anatomy of this Myriopod. The 

 Malpighian tubes diifer somewhat from those of its allies ; each tube is 

 doubled on itself in such a way as to form a great spherical knot, the 

 greater part of which lies in the semicircular chitinous elevations which 

 are placed at either side of the anus. The nerve-cord shows a greater 

 resemblance to that of the larval Julus and also of Chilopods than 

 does the nerve-cord of any other Chilognath with which the author is 

 acquainted. 



The chief interest of this form lies in the resemblance presented by 

 some of its anatomical characters to the anatomy of Chilopods. It 

 agrees, indeed, with the Chilognatha in the position of its generative 

 organs and the duplication of some of its segments, as well as in its 

 vegetable feeding habits, but it resembles the Chilopoda in the foi-m of 

 its spermatozoa, which are long and filiform and are contained in 

 spermatophores, in the general structure of its segments, the legs being 

 wide apart, and in the differentiation of the ventral nerve-cord. The 

 peculiar form of the second pair of mouth-appendages and the absence 

 of stink-glands, with the substitution for them of numerous spines as a 

 means of defence, are characters special to the genus. Polyxenus seems 

 to have preserved in its anatomy certain traces of its descent from the 

 ancestor common to the two classes of Chilopoda aud Chilognatha ; to 

 Mr. Heathcote it affords further reason for believing that the Myriopods 

 are descended from a Peripatus-like form, and as opposing their descent 

 from the Thysanura. 



5. Arachnida. 



Structure and Function of Spinning Glands of Araneida.f — Herr 



C. Apstein has not, like most of his predecessors, confined his investiga- 

 tions to Epeira diadema. In the Epeirid^e he distinguishes five kinds 

 of glands ; the glandul^e aciniformes are those which consist of a tunica 

 propria and an epithelium which exhibits in all its parts the same 

 reaction to staining reagents, whose longitudinal is hardly greater than 

 their transverse diameter, whose efferent duct has no epithelium but a 

 thick timica intima, and which ends in a spool, which is drawn out into 

 a fine tip. , The glandule pyriformes consist of a tunica propria and an 

 epithelium, which in its lower parts (or those near the efferent ducts) 

 stains more deeply than in the upper, whose efferent duct has a thick 

 tunica intima but no epithelium, and which ends in a spool with a very 

 small basal and fine short accessory piece. The glandulaB arapullace* 

 have a tunica propria aud an epithelium, the earlier part of which is 

 cylindrical, and then forms an arnpullaceous swelling; the efferent duct, 

 which consists of tunica projn-ia, epithelium, and tunica intima, forms a 

 double fold, and ends in a large spool cut off sharply at its end. The 

 glandulae tubuliformes vary hardly at all in diameter and end in a lar^e 

 spool. The glandulae aggregatfe have a wide and much-branched lumen, 

 the efferent duct of which is, in its median part, provided with protuber- 

 ances filled with cells; their sjjool is large and has an accessory piece 

 which draws out to a tip. The glaudulte tuherosae described by Meckel 

 and by Oeffinger Lave no existence. 



* Quart. Journ. Micr. Sci., xxx. (1889) pp. 97-106 (1 pi). 

 t Arch. f. Naturg., Iv. (1889) pp. 29-74 (1 pi.). 



