ZOOLOGY AND BOTANY, MICROSCOPY, KIC. 289 



5. Arachnida. 



Structure of Gamasid8e.*^Ivar Triigardh discusses a number of 

 morphological questions concerning Parasitid^. He notes the occur- 

 rence of two pairs of small dorsal shields between the anterior and 

 posterior shield in Sejus fogatus^ a very primitive feature, visible during 

 development in a few other genera. He also discusses the position of 

 the genital aperture, the various types of peritrema that occur, and the 

 hairs on the ventral shields. The so-called sternal shields are not true 

 sterna ; they are nothing but coxal plates. The sternal and metasternal 

 shields should be called syncoxal and metacoxal plates respectively. Of 

 the known Parasitidae the two most primitive genera are Zercon and 

 Sejus. 



Cribellum and Calamistrum in Spiders. t — Jeanne Berland has 

 studied these structures (a special pair of spinnerets and a comb) in a 

 number of sedentary (Cribellate) spiders of various families. All the 

 males, as well as the females, showed both structures. The young 

 males have l)oth as well developed as in the adults. Compared with 

 the females, which spin more and better, the males have less developed 

 cribellum and calamistrum. 



Poison-gland of Scorpions.^ — E. Pawlowsky has made a study of 

 the poison-gland in various types of Scorpionidas, Chactidae, and Buthida3. 

 There is considerable diversity of structure, from a simple smooth-wall 

 sac in Chactidaj to the sac with numerous folds in Buthidge. There 

 are few folds in Scorpionidse, and there has probably been a diphyletic 

 evolution. In all cases there are just two kinds of cells, glandular cells 

 and supporting cells. 



6. Crustacea. 



Fan Setas of Prawns. § — E. v. Lubicz Niezabitowski describes fan- 

 like setEe which occur in a variable percentage of individuals of HijJiwJyte 

 fuscigera^ H. gracilis, H. frideauxii, H. varians, and Virbius proteas. 

 The fan-setae are quite unique and not to be confused with pinnate seta?. 

 There is no doubt that they are sensory, but what sense they represent 

 is uncertain. Each seta is innervated by a fibre from a multipolar 

 ganglion cell. The fan-set^e are disposed in rows on the body and may 

 have some protective value in their likeness to the hydroids which grow 

 on lifeless objects. 



Cells of Isopod Caeca. II — A. Guieysse-Pellissier describes the very 

 large ceils which are characteristic of the enteric c^ca of Isopods. He 

 studied them in Anilocra frontalis Edw. At the distal end of the 

 caecum there is a zone of germinative cells, which increase rapidly and 

 show karyokinesis. After this germinative zone there is a zone of 

 growth in which the cells of moderate dimensions become huge. These 



* Arkiv ZooL, vii. (1913) No. 28, pp. 1-24 (30 figs.). 



t Arch. Zool. Exper., li. (1913) Notes et Revue, No. 2, pp. 23-41 (42 figs,). 



X Zeitschr. wiss. ZooL, cv. (1913) pp. 157-77 (2 plsj. 



§ Bull. Internat. Acad. Sci. Cracovie, 1913, pp. 10-23 (2 pis.). 



,i C.R. Soc. Biol. Paris, Ixxiv. (1913) pp. 392-4. 



