ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 495 



B. INVERTEBRATA. 



Lymphatic Glands of Cephalopods and Decapodous Crustacea.* — 

 M. L. Cuenot considers that the organ in Cephalopods which Ferussac 

 and d'Orbigny regarded as the pellicular appendage of the auricle, and 

 Owen as the horaologue of the second branchial heart of Nautilus, is a 

 lymphatic gland. Ho describes it as being bounded externally by a 

 thick epithelial layer ; its cavity is traversed by a complicated network 

 of connective tissue, in the meshes of which there are a number of 

 nuclei and of cells which exhibit the peculiar mode of development of 

 lymi^hatic cells; that is to say, whose nuclei become gradually surrounded 

 by refractive granules, which form the characteristic and constant con- 

 tents of amoebocytes. In the decapodous Crustacea there are two sets of 

 lymphatic glands ; the first and most important (and, above all, the most 

 constant) is situated in the gill between the efferent and aiferent vessel ; 

 the other may be seen in a Crab by carefully raising the dorsal carapace 

 and removing the cuticular matrix ; to the latter it adheres strongly. It 

 begins a little below the heart on either side of the middle line and 

 terminates at the level of the last pair of thoracic appendages ; each of 

 these glands has the form of an elongated pouch, which is slightly con- 

 tractile and communicates freely with subjacent venous lacunae. In 

 section it is seen to be bounded externally by the chitinogenous matrix ; 

 there then comes a zone of irregularly disposed muscular fibres, and 

 then a network of connective fibres, in the cavities of which there are a 

 number of nuclei and cells. The contents of a living gland were found 

 to consist of a considerable number of mature amoebocytes, filled with 

 refractive granules and develoj)ing nuclei, mixed with numerous reserve- 

 products. In the Brachyura these organs appear to be easily seen ; 

 among the Macroura they have been found active in Parjurus striatm 

 and Eupagurus Prideauxi, but greatly reduced in Galathea strigosa and 

 the Spiny Lobster. 



Mollusca. 

 o. Cephalopoda. 



Structure of Siphon and Funnel of Nautilus Pompilius.f — Mr. H. 

 Brooks has some preliminary remarks on this subject. The sijihon com- 

 mences in the first chamber as a ctecum, the closed end resting against 

 the inner surface of the apex of the shell ; it consists of a series of 

 tubular sections extending from septum to sej)tum, and increasing in 

 diameter as the chambers expand. Each section is made up of an 

 outer calcareous sheath, and an inner tube of conchiolin. In the outer 

 sheath there are spicules which overlie one another, and are arranged in 

 such a way as to form an exceedingly porous structure ; the spicules are 

 fusiform, and are, as a rule, arranged in stellate figures ; those that ex- 

 tend beyond the outer surface of the sheaths often end in irregular 

 knobs, many of which have the appearance of chestnut burrs. In very 

 young siphons, the sheaths are made up of slender threads, placed in the 

 same way as the spicules of the older sheaths. The spicules are made 

 up of slender transparent sticks of calcareous matter, which are held 

 together in bundles by organic matter. There seems to be a well-marked 

 period in the growth of the siphons when they first commence to form 

 spicules, but this, as yet, has not been exactly determined. 



* Comptes Kendns, cviii. (1889) pp. 863-5. 



t Proc. Boston Soc. Nat. Hist., xxiii. (1888) pp. 3S0-2 (2 pis.). 



2 M 2 



