42 S. LOVEN, ON POURTALESIA, A GENUS OF ECHIXOIDEA. 



overlooked, and have been much neglected, even in the latest works. Reaumur ^) was the 

 first who, early in the last century, observed them in a living f^chinus and described 

 some of their functions. But he was led to state that every single perforation, Mrou-D, 

 of the ambulacrum answered to a pedicel, and consequently that there were as many 

 pedicels as perforations. He also seems to have supposed that they are extended from 

 the interior and drawn in again through the pores. Sixty years afterwards these errors 

 were corrected by J. A. Gyllenhahl, ^) in the highlj^ remarkable paper in which he 

 demonstrated the animal nature of the fossils then named »ci'ystal apples", "calcareous 

 nodules)), or »Aetites», and ranged by Linn.eus among minerals, but which he pi-oved 

 to be "petrified animals of tlie genus Echinus or its nearest allies". He described two 

 species, the Echinus pomum, now Sphteronis poinum, and Echinus aurantium, now 

 Echinosphtera aurantium, both well-knoAvn forms of Cystoidea. Of the former he says: 

 uTentaculis procul dubio numerosissirais instnictuin (iisdera licet ipsis, prout mollioi'is substantiae, adeoque 

 petriticationis incBpacibus, iion potuerint non omaino privata fuisse fossilia individua): Cutis enim undique 

 pertusa est poris minutissimis, orbiculatis : Quorum gemini semper coUocati sunt intra caneellum minutum; 

 insequilateri-angulatum; fundo convexum; plerumque oblougum ct in singula extremitate pororum altero pertusum». 



This he explains thus: 



"As »the tentaclesu are to be understood those soft and elastic filaments which in all other Echini are 

 attached to the surface of the test, each over a pair of small perforations. All the species of Echinus hitherto 

 known possess cancelli on the surface of the test, corresponding with those described above in outline, in the 

 convexity of the bottom, and in the test being pierced, Avithin every single cancellus, by two minute perfora- 

 tions, one at each of its ends, the cancellus commonly being of an oval form. These two pores aflbrd the 

 communication between the internal parts and the tentacle, the basis of which occupies the entire cancellus, 

 and consequently covers both pores. In the new fossil species now described the cancelli are somewhat deeper 

 than in most other Echini, but in some of the irregular Echini I .lind those around the mouth to agree with 

 them ill this respect also." 



And he adds, against Reaumur: 



"I have examined Echini of different species, such as they had been taken out of the sea and afterwards 

 dried, and these I have placed in warm water in order to make their substance swell and resume its natural 

 shape, and thus I found that, instead of there being one tentacle to each pore, there is one tentacle correspon- 

 ding to each pair of pores." . . . »It follows that the pores are twice as numerous as the tentacles'). 



It will be noticed, that Gyllenhahl had an idea that in some of the Echini 

 irregulares of Linn.eus, the pedicellar pores near the oesophageal opening were somewhat 

 different from the rest. To the eminent Dane Otto Frederic Muller belongs, however, 

 the discovery, as early as in 1776, of the peculiar structure, in Spatangus purpureus, of 

 its circum-oral pedicels, of which, in the following year, he published a magnified figure, 



') Histoire de I'Academie Royale dcs Sciences. Annee MDCCXII. Avec les meinoires de mathematique 

 et de physique pour la raeme annee. Paris 1714, 4:o, Mem. p. 136, pi. 8. 



'-') Jon.\N AuRAii.^M Gyllenh.ahl, in his twenty second year, communicated to the B. Swedish 'Academy of 

 Sciences the above quoted memoir: Beskrifning pa de s.l kallade Crystall-iiplen och kalkbollar, sasora 

 petreficerade djur af Echini genus, eller dess niirmaste slagtingar. Kongl. Vetenskaps-Akademiens Hand- 

 lingar for Sr 1772, "Vol. XXXIII, p. 2;-i9. Translated into german in: Der Konigl. Schwedischen Aka- 

 demie der Wisseiischaften Abhandlungen aus der Naturlehre, Haushaltungskunst und Mechanik, auf das 

 Jahr 1772. Aus dem Schwedischen iibersetzt von Abraham Gotthelf Kiistner. Bd. XXXIV, p. 231. 

 Leipzig 1776. — J. A. Gyllenhahl, elder brother of Leonard Gyllenhaal, the eminent author of 

 "Insecta Suecica", was born in 1750 and died in 1788, as Director of the Copper-mines at Atvidaberg 

 in Ostrogothia. 



