REPORT ON THE DIATOM ACE/E. 97 



Eucampia, Ehrenb. 



This genus is defined by Fritchard in his History of the Infusoria (p. 937) as follows : — 

 " Frustules hyaline, imperfectly siliceous, cuneate, without terminal puncta, united in a 

 jointed spiral filament." With regard to this definition, it may be noted that although, 

 with the relatively imperfect microscopes used by Ehrenberg and W. Smith, by means of 

 which the minute sculpturing could not be detected, it was admissible to speak of the 

 frustules as hyaline, it is now possible to detect minute rows of points, so that that term 

 can no longer be made use of. 



Akin to the genus Eucampia, Professor Cleve of Upsala, in his paper entitled Exami- 

 nation of Diatoms found on the Surface of the Sea of Java, 1 instituted another genus 

 which he named Molleria, in honour of the well-known mounter of Diatoms, and crave a 

 definition which agrees with that of Eucampia, except that, in Molleria, the extremities 

 of the valves are produced into long processes, and the connecting membrane is orna- 

 mented with numerous costse (rudiments of diaphragms ?). That the presence of long 

 processes is an insufficient character upon which to establish a genus is manifest, and in 

 his Synopsis of the British Diatomaceas, W. Smith, 2 in representing a superb specimen of 

 Eucampia zodiacus, Ehrenb., indicates a slight puncturing on the valve, and traces of 

 several costae on the connecting zone. Hence the genus Molleria cannot be accepted on 

 the grounds quoted by Cleve. But in Molleria cornuta, Cleve, there exists a central nodule 

 which — as I observed in the case of a valve found in the original collection from the Sea 

 of Java, which was kindly placed at my disposal by Professor Cleve — is ornamented by 

 minute radiating puncta. Hence it only remained to be shown that, in Eucampia, no 

 central nodule occurred, in which case the genus Molleria could be reserved for those forms 

 of Eucampia possessing such a structure, and defined as indicated on page 98. 



Among the Challenger collections, series of cuneate frustules, without the terminal 

 point or appendage, and having all the peculiarities required by the definition of Eucampia, 

 Ehrenb. — except that, instead of being imperfectly siliceous or hyaline, they were fur- 

 nished with large granules — have been seen on several occasions. Hence the characters 

 of Eucampia, as established by Ehrenberg, may be emended thus : — Frustula cuneata in 

 duas insequales extremitates abrupte desinentia et in seriem spiralem conjuncta. 



Eucampia balaustium, n. sp. (Plate XVIII. fig. 5.) 



Valvis ellipticis convexis superne in duos insequales processus truncatos desinentibus et 

 medio inflatis ; granulis grandiusculis nullo certo ordine stipatis. In mari Antarctico. 



Each frustule here consists of two elliptical valves, which terminate above in two 

 unequal imperfect processes, between which a slight protuberance exists. The valves, 



1 Bihang k. Svensk. Vet. Akad. Handl, Bel. I. No. 11, p. 7. 



2 Smith, Synop. Brit. Diat,, vol. ii. p. 25, pi. xxxv. fig. 299., and Suppl., pi. lx. fig. 299. 



(bot. CHALL. EXP. PART IV. 1SSG.) J) 13 



