INVERTEBRATA, CRYPTOGAMIA, MICROSCOPY, ETC, 97 



are developed in this mesoderm, he found that the bodies in question 

 were, just as in the Spongite, developed in the cells. The nucleus of 

 the cells disappears in time, and the calcareous body, at first sur- 

 rounded by the protoplasm, finally becomes completely free. 



In examining Claviilaria crassa the author had the assistance of 

 Professor Marion. They found that the ova undergo complete seg- 

 mentation, and that the spheres become arranged in two layers. The 

 cells of the endoderm soon become separated into two layers, of which 

 the inner is used up during the processes of metamorphosis. The 

 observations of Marion on the succeeding stages lead him to think 

 that the " mesoderm," with its external epithelium, should be simply 

 regarded as representing the ectoderm, and in this view Kowalevsky 

 completely agrees. Marion found that the history of its development 

 was in Claimlaria completely similar to that which was seen in 

 Sympodium, with this sole exception, that the calcareous spicules 

 appear somewhat later. 



Skeleton of Corals. * — Herr von Koch finds that the ordinary 

 dictum that the tlieca of the corals is the calcified basis of the sup- 

 porting lamella of the polyp-wall is not always correct. He has 

 examined a number of the Aporosa, and has observed that the theca 

 (Mauerhlatt) is only connected with the soft body-wall at its base. 

 Taking as an example the common Caryophyllia cyatkus, he shows 

 that the mantle is formed by a supporting membrane, which is in- 

 vested externally by the ectoderm and internally by the endoderm. 

 At the base of the several chambers into which the interior of the 

 polyj) is divided there are radiating septa which, consisting princi- 

 pally of a calcified connective substance, are thickened towards their 

 periphery and are also united together. The wall thus formed divides 

 the partitions of the chambers into a C(!ntral and a perijihoral jiortion. 

 As the polyp grows, the latter becomes completely fxiscd into a single 

 mass, and, with the gradual death of the creature in the peripheral 

 portions of the base, there becomes apparent a naked, calcareous 

 surface. 



A new species of Clavularia (ochracea) is to be distinguished from 

 Cornularia cornucopice by having tlie hyaline substance of the meso- 

 skcleton very richly developed, and its ccto-skeleton far less so. 



In the si)icules of Alcyonaria the author has observed that the 

 crystals are concentric and very regularly arranged, but that their 

 axes more or less cross one another ; in the examination of other 

 forms of calcification the author states that ho has met with very 

 considerable difiiculties. 



Histology of Crateroloplius tethys.f — This f^l^cc\cBoi Lnccrnar'uJcB 

 is studied by Dr. ( ). Kling, of Frankfurt; the account of tlic minuto 

 striicture being preceded by a general descrii)ti()n of the anatomy. 



1. Ectoderm. — The cells on the aboral surface c»f the bell and on 

 the pedicle are strongly pigmented cylinder-cells, jji-ovided with 

 nematocysts and glands. They secrete a thick cuticle, divisible into 



* 'Morpliol. .Tiihibuch,' v. (1S71») p. 310. 

 t Il)itl., [>. 111. 

 VUL. 111. H 



