300 Scientific Intelligence. 
and the subdivision into subfamilies is likewise original. ‘The principal 
changes in the nomenclature result from the revival of names proposed 
d by Prof, 
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dontoide, Notidanoide, Spinacoide, an inoide. 
3. On the mode of development of the marginal tentacles of in ie 
Meduse of some Hydroids; by A. Acassiz. 14 pp., 8vo. From a 
Proc. Bost. Soc. Nat. Hist., vol.ix, August.) On Alternate Generation” 
Annelids, and the Embryology of Autolytus cornutus; by ose 
p ro . Soe. 
the marginal tentacles of Meduse. Designating each new intert co 
series by ¢ and a number, added as an index expressing the order 10 ®™ 
of the several series, he makes out a formula for the order 
ment, and also for the number of tentacles. Thus, in a young Tiarop 
the formula for the number of tentacles is 
2i=4T ,+-41,-+167, 241, . ai | 
or in other words, the sum of the number of tentacles equals 4 of the 416 
first in the order of time, +-4 of the second (or those next developed), ee 
of the third. In two older stages of the Tiaropsis, the formulas af 
St=4T ,-+-47,4-16t,+-8t, +82, 401, 
and St 4T 4-4t,4+161,+8¢, +87, +161, = 56t 
We refer to the paper for other examples of these important results. 
