152 HBXDUY, OX THK HULL PLEUROSIGMA VASCIOLA. 



NaV; more, it is perfectly true to say that organic creation 

 itself began with " a microscopic specimen." 



On the Hull Pleurosigma fasciola. 

 By Wm. Hendry, Surgeon. 



Relative to this diatom, Mr. SoUitt, iu the ' Micro- 

 scopical Journal' for October, 1860, p. 48, remarks: — ''Of 

 this diatom, the kind we find near Hull, are very small, and, 

 consequently, the markings extremely fine ; the finest being 90 

 in "001", but the Fasciolae we get from Boston in Lincoln- 

 shire, are many of them so large, that there are not more than 

 50 strice in "OOl". I have frequently seen in the largest-sized 

 Fasciola oi Boston, the longitudinal and transverse striae, at 

 the same time, with the half-inch objective." 



" The length of the finest Hull Fasciola (Mr. Sollitt states) 

 is under the ^3-^0^^ o^ ^^ inch, while some of the Boston Fas- 

 ciolse measure more than the i-^-oth of an inch.'' 



I do not deny that the usual character of the P. fasciola 

 obtained in the neighbourhood of Hull, may be of the finer 

 description, and the same may be equally true of most other 

 places. The coarser, or so-called " Boston" variety, may, 

 however, also be found at Hull ; and only a few weeks since, 

 when out in company with Mr. Harrison, we obtained a 

 copious gathering in the Hull timber-ponds, containing spe- 

 cimens of the larger kind, in which the longitudinal and 

 transverse striation were simultaneously shown with great 

 boldness under a ^-inch, and were very evident also with the 

 T^th-inch objective. Hence the hitherto somewhat hackneyed 

 phrase of " 'UnW. fasciola," and " Boston /a^do/a," the former 

 being regarded as exclusively fine and the latter as exclu- 

 sively coarse, is no longer admissible. And as regards the 

 number of lines in each kind respectively, this must be hence- 

 forth regarded as indeterminate, or as merely embraced be- 

 tween the two extremes above stated. 



The Hull Fasciola, thus widely ranging between fine and 

 coarse, only furnishes another link to the chain of evidence 

 contained in my former published communications on the 

 irregular development of striation of the usually considered 

 high order of test-objects amongst the diatomacese. 



Turning to the elaborate list of diatoms published in the 

 'Microscopic Journal,' for April, 1860, as occurring in the 



