368 HAWAIIAN AXD OTHER PACIFIC ECHINI. 



Parasalenia. 



A. Agassiz, 1863. Bull. M. C. Z., I, p. 22. 

 Type-species, Parasalenia graliosa A. Agassiz, 1863, 1. c. 



This is a very interesting genus and its affinities are by no means clear. The 

 ambulacra are echinoid, the anal plates are like Arbacia, while the form of the 

 test is like Echinometra. The spines are externally hke Echinometra and the 

 differences internally are hardly as important as Mc Intosh and Alortensen seem 

 to think. When compared with Echinometra-spines of the same size, those 

 of Parasalenia are not essentially different. The lantern, teeth, and auricles are 

 like those of small Echinometras, except that there are apparently' no projections 

 on the epiphyses for the support of the teeth. It is clear from these important 

 structures about the mouth, that there is no near relationship to .\rbacia, and 

 the pedicellaria? confirm this conclusion. Except that the lateral tooth is lacking 

 on the left side of the narrow blade, there is nothing about the globiferous pedi- 

 cellarise to distinguish them from those of Echinometra, and the other forms 

 are even less peculiar. The calcareous spicules in the pedicels of Parasalenia 

 are very characteristic but they do not indicate relationship to any othe r group. 

 On the whole it seems that Parasalenia is an isolated offshoot from the echinid 

 stock from which the Echinometridae have sprung and that it is not properly a 

 part of that family from the phylogenetic point of view, but as a matter of con- 

 venience it may be placed therein. 



Whether the genus contains more than one valid species seems uncertain. 

 Owing to insufficient material the status of Pohlii is doubtful. Typical specimens 

 of the two nominal species are very different but as is so often the case, there 

 are certain specimens which are perfectly intermediate at least in many ways. 

 Tlx^ rod coloration of Pohlii is very noticeable and extends even to the calcareous 

 matter in the pedicellariir but specimens of gratiosa are sometimes quite red. 

 especially when youn^. The primary sj)ines of gratiosa are sometimes lianded 

 and if such specimens are also more or less red, the resemi)lance to Pohlii is very 

 marked. In our specimens of Pohlii, genital 3 is excluded from contact with the 

 IxM-iproct, by the meeting of genitals 2 and 4. but whether this is a constant 

 specific characl(»r, is not known: if it is, it is an excellent one. In our .'specimens, 

 globiferous i)e(iicellarite are extremely rare, and tridentate fairly common in 

 gratiosa, \\h\\v in Pohlii, the globiferous are abundant while the tridentate are 

 very vnrc; but it may Ix^ doubted if tiiis difference holds thoughout the species. 



What seem to be the real specific differences may be stated as follows: — 



