472 Miscellaneous. 



The pedicell. gemmiformes have the same function, and in grasping 

 they are assisted by the secretion in the j^landular sacs of the valves, 

 as experiment shows. In EcMnus microtuhercvlafus the gland- 

 bearing pedicellarise stand chiefly on the dorsal surface and serve, 

 as I have been able to ascertain from many animals kept in the 

 aquarium, to hold fast fronds of seaweeds &c. with which the sea- 

 urchin masks itself both when at rest and when in motion. In this 

 the slimy secretion of its glandular pedieellariae is of the greatest 

 service. — Sitzuvgsberichte dcr Jenaischen Oesellschaft filr Medicin 

 vnd Naturwissenschaft, 1886. 



Discovery of the Heart in Gamasus. 

 To the Editors of the ' Anncds and Magazine of Natural History.' 



Gentlemen, — My attention has just been called to a translation 

 in youi' February number of Prof. C. Claus's paper in the ' Anzeiger ' 

 of the Academy of Yienna relative to Herr Willibald Winkler's 

 supposed discovery of the heart in Gamasus. If Prof. Claus and 

 Herr Winkler imagine that the latter has observed this organ for 

 the first time they are in error. It was noticed in 1876 by Dr. P. 

 Kramer, then of Schleusingen, who published his remarks on the 

 subject in the Archiv fiir iS'aturg. xlii. Jahrg. 1 Bd. p. 65, as one 

 paragraph of a paper entitled '• Zur Naturg. einiger Gattungen aus 

 d. Familie d. Gamasiden." The paragraph is as follows : — 



" Das Circulationsorgan. Bei Gamasus fiudet sich endlich im 

 letzten Drittel des Hinterleibes ein lebhaft pulsirendes Herz. Da 

 bei den raeisten Arten die verhiirtete Riickendecke die Beobachtung 

 der innern Organe unmciglich macht, so eignen sich zur Auffindung 

 des Herzens nur unerwachsenc oder eben durch cine Hiiutung gegan- 

 gene Thiere, an denen es aber leicht und sicher erkannt werden kann . 

 Seine Bewegungen sind von denen der Excretionsdriise natiirlich 

 auf das bestimmteste verschieden, auch entspricht seine Lage ganz 

 dicht unter der Haut der Lage desselben Organs bei andern Glieder- 

 thieren." 



Dr. Kramer's observation is perfectly well known amongst Aca- 

 rologists and has been publicly referred to by Dr. Haller, myself, 

 and others in our writings. It will be seen that Dr. Kramer did 

 not describe the valves, and it is perhaps fair to say that in some 

 (juarters doubts have been entertained whether the organ really was 

 a heart or whether the movement was not more allied to the strong, 

 presumably peristaltic, movements which may be observed in the 

 caeca of the alimentary canal in young Gamasids. If Herr Winkler's 

 observation of the valves be reliable it will, of course, strongly con- 

 firm Dr. Kramer's discovery. 



Prof. Claus may possibly not find it so easy to trace the organ in 

 other families of the Acarina, as, judging from his remarks, he may 

 very naturally anticipate ; at all events, I am not aware that it has 

 liitherto been traced in any other, although, as above stated, 

 Kramers observation has been well known for several years. 



I am, yours obediently, 

 Cadogan Mansions, Sloane Square, Albert D. Michael. 



April 17, 1886. 



