MUSEUM OF COMPARATIVE ZOOLOGY. 335 



is readily distinguished by its larger tentacle scales, and longer, more 

 tapering arm-spines. A. Sundi ualli is also similar, but has the, side niouth- 

 sliields meeting within, and very broad, and the arm-spines more stumpy. 

 I. Slimpsonii, hitherto only known by Liitken's description (Addit. ad Hist. 

 Ophiur., Part II, p. 116) has the proportions of the disk and arms much 

 as in A. grand isquama. The mouth-shields are longer than broad; the 

 side mouth-shields small and narrow, meeting within, closely soldered to 

 the surrounding parts, and, at their outer end, to a very small rudimentary 

 under arm-plate ; at base of arm, one very small tentacle scale ; further 

 out, none at all ; radial shields closely joined at their outer ends ; within, 

 separated by a couple of long scales: five short, stumpy arm-spines. 



Remarks on the Croups in the Genus Am.ph.iura. — Any one who is really 

 familiar with the range of species in this genus will, on the one hand, 

 recognize striking differences, while, on the other, he will find a real diffi- 

 culty in dividing the groups in away to bear criticism. Liitken very prop- 

 erly set off the genus Ophiactis : and I have since separated the Amphiu- 

 rcr with spiny disks under the name Ophiocnida, and those with a fence 

 of scales round the discs as Ophiophragmus. Professor Agassiz had already 

 recognized the generic position of the species with a naked disk below, 

 under the name of Hemipholis. Mr. Ljungman * further distinguishes a 

 genus Amphipholis, of which the type is -1. Januarii, which seems to belong 

 with such species as A. elegans (Amphiura squamala Ltk.) and A. tenera. 

 It is by no means clear on what characters Mr. Ljungman grounds this new 

 genus; because, after giving a number of characters common to nearly the 

 whole of the old genus, he concludes with this distinction : " A generibus 

 Hemipholide et Amphiura numero et dispositione papillarum oralium dif- 

 fert." But the species which he includes under AmpJiipholis do not at all 

 agree among themselves in the number or disposition of their mouth-pa- 

 pilla? ; e.g. A. tenera, A. occidentalis, and A. atra. There certainly is a 

 group which includes Amphiura elegans (squamata), A. tenera, A. riolacea, 

 and -1. pvgetana, whereof the members are not only closely allied gener- 

 ically, but are even difficult to distinguish specifically, though coming from 

 faunae the most widely separated. Thus, Mr. Ljungman gives A. elegans 

 as coming from the shores of Northwestern Europe, and also the Cape of 

 Good Hope, (!). And since this species has been shown to vary so consid- 

 erably in its arm-spines, it seems difficult to separate it any longer from 

 A. tenera of the West Indies; and, further, from A. riolacea, A. microdis- 

 cus, and .1. Punlarenai of the Pacific coast of America. Should all, or a 

 part, of these species prove identical, -we must look upon this animal as the 

 common thread that binds together distant faunas, just as characteristic 



* Ljungman, Ofversigt af Kongl. Yet. Akad. Forhand., 1S6G, p. 165. 



