ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 57 



5- Arachnida. 



Alteration of Instinct in Spider.* — Jeanne Berland observed that 

 females of Nemoscolus laurse, which were induced to make webs in Bore! 

 tubes, altered the plan from an orb with a large diameter to a sector 

 elongated vertically and with few rays (as in the genus Hyptiotes). In 

 adaptation to a narrow space the characteristic form of web was pro- 

 foundly altered. 



Cardiac and Skeletal Muscle of Scorpion. f—H. E. Jordan finds 

 that the striped muscle of the Florida scorpion is very similar to that 

 of Limulus, and accordingly conforms more closely to the Vertebrate 

 type of striped muscle than to the Arthropod type as exemplified by 

 certain insects and by the sea-spider. The cardiac muscle of scorpion 

 and of Limulus conforms with Vertebrate heart muscle in its syncytial 

 structure, in the more or less regular radial arrangement of the myofibril 

 bundles (lamellfe), and in the definite character of the relatively less 

 complex cross striping. The skeletal muscle also of these forms agrees 

 with Vertebrate skeletal muscle with regard to the major stripes, and in 

 the absence (or extreme tenuity) of the mesophragma and the accessory 

 disc (N-disk) of Engelmann and Rollet, conspicuous in certain insect 

 muscles. There is in the scorpion an essential identity in microscopic 

 structure between the cardiac and skeletal muscle. The axial location of 

 the nuclei, the radial lamellar arrangement of the myofibrils, and the 

 relative simplicity of the striations all indicate a relatively low degree of 

 differentiation. Many details as to structure are communicated. 



Rare Hydracarid.|— W. Williamson reports the occurrence of a 

 female of Lebertia densa Koen. at Craigallian Loch, and gives a descrip- 

 tion and figures. The rare species does not seem to have been recorded 

 since Koenike found it at Harburg in 1902. Its discovery at Craigallian 

 brings the number of British species of Lebertia up to eleven. 



• New Parasitic Acari.§— Stanley Hirst describes Chirodiscoides caviee 

 g. et sp. n., a curious minute mite found on the hairs of the posterior 

 region of the guinea-pig's back. As in Chirodiscus the anterior legs are 

 adapted to form hair-clasping organs. During copulation the male 

 attaches himself to the generative nymph by little suckers on the venter 

 and also by the elongated legs of the fourth pair, the hook of the tarsus 

 becoming fixed in the projecting posterior margin of the second epimeron. 

 A description is also given of Demodex muscardini sp n., from a dormouse,, 

 and D. erinacei sp. n., from a hedgehog. 



Leg-muscle of Sea-spider. || — H. E. Jordan finds material of ex- 

 ceptional clearness in the leg-muscle of Anoplodactylus lentits. It differs- 

 from that of Limulus in being of the typical insect type, while that of 



* Arch. Zool. Exper., Ivi. (1917) Notes et Eevue, No. 5, pp. 134-7 (4 figs.). 



t Anat. Record, xiii. (1917) pp. 1-20 (21 figs.). 



X Scottish Nat., 1917, pp. 271-4 (2 figs.). 



§ Ann. Mag. Nat. Hist., xx. (1917) pp. 431-4. 



II Anat. Eecord, x. (1916) pp. 493-508 (7 figs.). 



