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 pai'allels. 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 memohs 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 ; otliers 

 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 life. 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'Echinodcvmes,' No. L'. [We liave been 

 favoured by Mr. Charlesworth witli the comnumicatiou and translation of 

 the present article. — Ed.] 



