144 



ECH1NOIDEA. II. 



To this species evidently belongs the specimen figured by Koehler (Sur les Echinocardium 

 de la Mediterranee. PL 4. 10) as well as that figured by Gasco (Op. cit), and it may perhaps be allowed 

 to suggest that in several other instances the two species flavescens and intermedium have been con- 

 founded. The existence of flavescens in the Mediterranean is proved by Figs. 4 and 5 of the paper 

 quoted by Koehler which are certainly true flavescens and have been made after specimens from the 

 Mediterranean, as expressly stated by Professor Koehler in a letter to me. 



The American specimens referred to Ech. pennatifidum will probably be found not to belong 

 to that species either. From the description in the Rev. of Echini p. 351 it appears that the Ameri- 

 can form differs from pennatifidum in several regards. The periproct 1 is said to be somewhat pear- 

 shaped; in pennatifidum it is more or less transversely elongate. The internal fascicle is very elong- 

 ated, elliptical, including an extremely narrow space* ; in pennatifidum it is more angular, as is very 

 well seen in Koehler's Fig. 9. PI. IV. (Monaco). The apex is anterior, and placed at a distance of 

 about one fourth the longitudinal diameter of the test from the anterior extremity, thus differing 

 strikingly from either E. flavescens or E. cordatum, in which the junction of the ambulacra is either 

 almost central or eccentric posteriorly*; in pennatifidum the apical system is, however, not anterior 

 but central or even a little eccentric posteriorly. The posterior ambulacra are much shorter than in 

 E. flavescens. To illustrate this feature I give here some measurements; they show clearly that the 

 posterior petals (which is evidently the meaning) are distinctly longer in pennatifidum than in flavesc- 

 s^ the reverse case to what is found is Agassiz' specimens. 



Ech. pennatifidum. 



Ech. flavescens. 



Also the form of the test seems to be different, judging from the figures given in the Re- 

 vision* (PI. XX. i), the posterior end being more pointed in the American form, whereas in the Euro- 

 pean form it is rounded. Unfortunately nothing is known of the labrum, the number of ambulacral 

 plates reaching within the subanal fascicle, the number of pores in the petals, the pedicellariae and 

 spicules. But the differences pointed out here seem scarcely to leave any doubt that the American 

 specimens referred by Agassiz to Ech. pennatifidum are really a distinct species; if that proves to 

 be so, this species must keep the name Ech. lavigaster A. Ag., by which it was first described (unless 

 it turns out to be identical with the pliocene Ech. orthonotus Conrad). In any case it cannot be re- 

 garded as an established fact that EC/I, pennatifidum occurs in the American waters, before it has been 

 stated by a renewed careful examination that the American specimens really belong to this species. 



anal area. 



1 Strictly speaking it is said of the anal opening, but I suppose I am not mistaken in taking it to mean the whole 



