Prof. Agassiz on the Echinodermata. 189 and with a success which cannot be considered unsatisfactory. In temperate latitudes the above details will furnish a guide, and also the comparative table of the equatorial and tempe-rate zones. The latter will not be found to deviate much in the warmer temperate climates, but is decidedly too great for higher parallels. Among the colder of these climates a mean of from 200 to 250 feet may be used for a depression of 1° of the thermometer. [To be continued.] XXIII. — Observations on the Progress recently made in the Natural History of the Echinodermata. By Prof. Agassiz *. With a view of rendering more complete the results which, in the preface to the first of these Monographs, I have given of my investigation of the Echinodermata, I shall here offer some remarks upon the progress recently made in the natural history of this class. The memoirs which have appeared during several years past, or which are at the present moment in course of publi-cation respecting these animals, are sufficiently numerous. Of these some relate to their classification in general, or to the descriptive natural history of the genera and species ; others have reference to their anatomy, both actual and comparative, or it may be that they embrace the study of the numerous fossils which have represented this class at the epochs of the development of organic Hfe. It is in this order that we shall now pass them in review, and in conclusion I shall give some account of the collections which I have lately had the opportunity of examining. As these different departments of inquiry in the natural history of the Echinodermata have advanced rapidly, it is the more to be regretted that a knowledge of their habits, of their alimentation, of their growth, of the functions of their organs, &c., should as it were rest stationary, if we except some de-tached observations upon the European species. The only work [among the publications coming under con-sideration] which embraces the entire class Echinodermata, is the delightful volume which Mr. Edward Forbes has pub-lished upon the British species (History of British Starfishes and other animals of the class Echinodermata, 1840-41). He divides them into six orders : — 1st, the Pinnigrada or Crinoi-dece ; 2nd, the Spinigrada or Ophiuridce, which he subdivides * From the ' Monographies d'Echinodermes/ No. 2. [We have been favoured by Mr. Charlesworth with the communication and translation of the present article. — Ed.]
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