78 



IIARDWICKE'S SCIENCE-GOSSIP. 



(The hypothetical cross section (fig. 45) will save 

 much explanation. I believe that, if anything, the 

 lower plate rises more nearly to a level with the 

 dorsal than I have shown.) I was unable to make 

 out that either of the plates were infolded, and, having 

 but one specimen, I dared not make use of caustic 

 potash to solve the comparatively unimportant point. 

 On looking at fig. 44 (dorsal view), three moderately 

 conspicuous lines are seen. The outer line, broken 

 only by the superposition of the foot, is the edge of 

 the ventral plate, the next line, unbroken and there- 



Fig. 44. — Dorsal view of Euchlanis subversa. 



fore above the foot, is the edge of the smaller or 

 dorsal plate, and the V-shaped inmost line is the 

 optical presentment of the fold in the membrane 

 connecting the two plates (as at the point D of 

 transverse section). On reference to Diplois propatula 

 in the figure of which all three lines will be seen, 

 Mr. Gosse will be found to state that the V-shaped 

 line seen by him is the edge of a cleft in the larger or 

 dorsal plate of that species, and it is principally on 

 account of this cleft, that he places the species in the 

 genus Diplois and in the family Salpinadse. In my 

 specimen, although the lines are equally visible, I 



satisfied myself by careful and repeated observation 

 with the highest combination at my command 

 (quarter inch obj. c eyepiece) that there was not 

 cleft on either the dorsal or ventral plate. I could 

 easily focus organs lying above, and organs lying 

 below the level of the V-shaped line. That the 

 smaller plate was the dorsal was proved by the 

 presence of the brain and dorsal antenna on the same 

 level. 



There was equally the appearance of three spines 

 at base of foot. These, on minute examination, were 

 also found non-existent. The centre spine is the 

 optical presentment of an acute angle formed by the 

 attachment of the membrane aforesaid to the dorsal 

 plate, being in fact the point of the V ; the outer 

 pair seemed to me to be two little flanges arising 

 from the ventral plate and probably a side protection 

 to the foot, which further is protected above by a 

 small sub-square plate. 



The toes in my specimen are long, slender, rod- 

 like, and slightly out-curved, agreeing thus with 

 Dr. Collins' specimens of Diplois propatula. The 

 brain was large, composed of many round globule- 



DORSAL 



FOLD OF 

 MEMBRANE 



VENTRAL 



Fig. 45. — Hypothetical transverse section of Euchlanis 



subversa. 



like cells, fairly transparent, and the eye, seated upon 

 the inner side of brain, had the appearance of two 

 eye-specks partially fused into one. The dorsal 

 antenna was distinct at anterior point of brain. 



At the points marked ee I thought I could dis- 

 tinguish two minute oblong openings bounded by 

 a slightly thickened ring of harder substance than the 

 membrane adjoining. Length, including toes, about 

 ijj inch. 



The divergence from Mr. Gosse's description was 

 so marked whilst the animal, viewed dorsally, so 

 much resembled his figure, that I thought it well to 

 submit my observations to Dr. Hudson, and I proposed 

 to him in a letter written early in October that the 

 species should be transferred to the genus Euchlanis. 

 In his reply he informed me that he had not himself 

 seen the species, and suggested that, to avoid con- 

 fusion, my specimen should be described under a new 

 specific name. I made further fruitless enquiry as to 

 the occurrence of Diplois propatula, and finally sent 

 to Science-Gossip the short request printed on 

 page 41 (February 1890). On its appearance I was at 

 once favoured with a communication from Mr. Percy 

 Thompson. In brief he was able to tell me that on 

 19th October he had found, examined, sketched and 

 described in notes, a specimen agreeing in every 



