ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 57 



more than five rays, and those in which, so far as we know, the 

 number five is constantly retained." For these two groups the terms 

 Heteradinida and Pentactinida are suggested. Among the former 

 we find that some of the species have more than one madreporic 

 plate ; the secondary divisions, therefore, are named polyplacid and 

 monoplacid. The value and character of the number of rows of 

 adambulacral spines is next discussed, and the terms MonacantMda, 

 Diplacanthida and PolyacantJiida are applied to the forms in which 

 there is one, two, or more than two such rows. Some species are 

 shown to have their madreporic plate encircled by spines, and these 

 forms are distinguished as being echinoplacid. The next character 

 used depends on the arrangement of the spines, " on special local 

 modifications of the integument, which may be known as special 

 plates " ; such forms are autacanthid ; those in which the more 

 ordinary arrangement obtains are known as typacanthid. The last 

 character used for the formation of small groups depends on the 

 form of the spines on the abactinal surface ; and here we have 

 simplices, rarispinosce, ohtiisispinosce, and acutispinoscB. 



After a table, in which this system of grouping is worked out, 

 the author passes to the " mode of formulating results," using a certain 

 number of symbols, and distinguishing heteractinid from pentactinid 

 forms by placing over their formulae the mathematical sign of the 

 square root. Short formulae are given for most of the known 

 species. Thus, for the well-known A. ruhens, we have the formula 

 2 ois, for it is diplacanthid (2), anechinoplacid (a), typacanthid {t), 

 with simple dorsal spines (s). Again, »Jlp is sufficient to distinguish 

 A. calamaria as a monacanthid, polyplacid, heteractinid form. " If 

 we know, as we do in this case, further details, we may write the 

 formula Vl paa' ; or, in other words, in addition A. ccdamaria 

 has no spines round its madreporic plate, and the dorsal spines are 

 placed on special plates." 



The author then makes some observations on the species of 

 Asterias, found in the British seas, and concludes with the description 

 of five new species : A. pMlippii, A. inermis, A. verrilli, A. spirahilis, 

 and A. rollestoni, for all of which, as also for A. japonica, of which a 

 description is given, the author gives the " general formula." 



Spines of Asteroidea.* — At the conclusion of a description of a 

 new species of Archaster (J., magnificus), Professor F. J. Bell points 

 out that in littoral species, at any rate, the strength and number of 

 the spines is in inverse proportion to the stoutness of the skeletal 

 plates ; when these are strong the star-fish is enabled to withstand 

 the bite of an enemy ; but when they are weaker, a defensive apparatus 

 is provided in longer, stronger, and stouter spines, 



Coelenterata. 



Prodrome of the Anthozoan Fauna of Naples.! — Dr. A. Andres 

 here gives a systematic catalogue of the species, with synonymy, &c., 



* Auu. and Mag. Nat. Hist., viii. (1881) pp. 440-1. 

 t MT. Zool. Stat. Neapel, ii. (1881) pp. 305-71. 



