ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 445 



(down to 100 metres) of the Lake of Geneva ; and, after taking due 

 account of the varieties, comes to the conclusion that L. profunda is an 

 abyssal variety of the littoral L. ovata, and L. abysskola of L. palustris. 

 It may be noted that the deep-water forms, contrasted with the shore 

 forms, are mainly carnivorous, that they breathe cutaneously, that they 

 have smaller but not degenerate eyes, and that they are less prolific. 



Salivary Glands of Nudibranchs.* — W. Brygider has investigated 

 the microscopical structure of the salivary glands of Nudibranchs, with 

 a view to their classification and nomenclature. In Nudibranchs the 

 external mouth-orifice opens into a tube, the terminal portion of which 

 widens into a mouth from which an aperture through a muscular sheath 

 opens into the pharyngeal cavity, the thick muscular walls of which 

 project outwards like a ball. This cavity encloses the tongue and 

 radula, and it is bounded anteriorly by the jaw, which rests on its lateral 

 walls. An analogous series of parts occurs in Doriopsis, though tongue, 

 radula, and jaw are absent. In addition to skin-glands, the investigator 

 found two pairs of well-developed glands, one pair opening into the 

 pharyngeal cavity, the other into the anterior mouth-tube. The 

 pharyngeal glands are the true salivary glands, the others are secondary 

 salivary glands. All Nudibranchs possess the pharyngeal pair ; they 

 may or may not possess the other. The Porostomata have an unpaired 

 mouth-gland in addition to the pharyngeal pair. In general appearance 

 the salivary glands are of three types, tubular (Spurilla), sac-shaped 

 (Doto), or lobed. The characters common to each pair in different forms, 

 and their distinctive differences, are described, and the question of their 

 homology is discussed. 



5. Lamellibranchiata. 



Musculature and Muscles of Anodonta cellensis.f — Artur Briick 

 first describes the musculature of the foot and the visceral sac, dis- 

 tinguishing four layers and showing how they are correlated. He then 

 describes the structure of the adductor muscles and those of the mantle- 

 margin. The minute structure of the muscle in the larva and adult 

 is then described. The origin of the longitudinally striped and the 

 spirally striped muscle is dealt with, and the development of fibrils from 

 plastosomes. The spirally striped muscle with heterogeneous fibrils must 

 be regarded as a stage in the evolution of cross-striped muscle. Three 

 chief types of muscle may be distinguished : — 1. Longitudinally striped 

 or smooth muscle-fibres with homogeneous fibrils. 2. Muscles with 

 simple heterogeneous fibrils ; in some bivalves (e.g. Pholas) with longi- 

 tudinally striped fibres ; in Anodonta and Unio with spirally striped 

 fibres. 3. Muscles with typical cross-striping, characterized by the 

 appearance of the Z-line. 



Kidneys of Anodonta.|— Wilhelm Fernau publishes the second (the 

 histological) part of his paper on the structure of the kidney in Anodonta 



* Zeitschr. wiss. Zool., ex. (1914) pp. 359-418 (3 pis.). 

 t Zeitschr. wiss. Zool., ex. (1914) pp. 481-619 (81 figs.). 

 X Zeitschr. wiss Zool., ex. (1914) pp. 304-358 (20 figs.). 



