144 



ECHINOIDEA. II. 



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

 de la Méditerranée. PI. 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 tvvo species flavcscois and intermedium have been con- 

 founded. The existence of flavescevs in the Mediterranean is proved b>- Figs. 4 and 5 of the paper 

 quoted by Koehler which are certainly \x\\<t flavcscens 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 Ecb. pennatifidum will probably be found not to belong 

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

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

 shaped; in pennatfiduvi it is more or less transversely elongate. The internal fasciole is «:verv elong- 

 ated, elliptical, including an extremely narrow spaces; in pennatifidMvi it is more angular, as is verv 

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

 about one fourth the longitudinal diameter of the test from the auterior extremitv, thus differing 

 strikingly from either E. flavescens or E. cordatum, in which the jnnction 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; thev show clearlv that the 

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

 ens, the reverse case to what is found is Agassiz' specimens. 



Ech. pentiatifidum. 



Ech. flavescens. 



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

 vision ;■ (PL 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 

 piates reaching within the subanal fasciole, the number of pores in the petals, the pedicellariæ and 

 spicules. But the differences pointed out here seeni 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. lævigaster A. Ag., by which it was first described (unless 

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

 garded as an established faet that Ech. 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. 



Strictly speaking it is said of the anal opening, but I suppose I aui not mistakeu in takiug it to mean the whole 



