SALPINAD.E. 83 



long side (the dorsal) unsewn, whose edges remain approximate, yet separate. 1 Both 

 ends run off into projecting points, which are grouped into four series, occipital and 

 pectoral in front, lumbar and alvine behind ; and these terms may be convenient for 

 definition. The head can be retracted wholly within the lorica ; but the foot only 

 partially, and the toes never. These are moderately long, blade-shaped, acute, straight, 

 divergent. The eye is usually conspicuous, single, rather large, placed on the occipital 

 end of an ample brain. The mastax is large, globose, the mallei and incus well- 

 developed, the former many-fingered. A bristle-bearing antenna is protruded between 

 the occipital spines. P.H.G.] 



S. MUCKONATA, Ehrenberg. 



(PI. XXII. fig. 1.) 

 Salpina mucronata . . . Ehrenberg, Die Infus. 1838, p. 469, Taf. Iviii. fig. 4. 



[SP. CH. Occipital spines two, procurved ; pectoral two, wide apart, separated by 

 a deep sinus ; lumbar single, short ; alvine two, recurved, separated by a wide and deep 

 sinus ; dorsal parts of the lorica minutely stippled. 



The lorica is somewhat three-sided, the back arched, and doubly ridged, with a narrow 

 but deep furrow ; the sides gracefully swelling ; the belly nearly flat. The two occipital 

 spines, antler-like, are bent forward and slightly approximate at their points, with a 

 deep sinus between their bases. From the two edges of this sinus spring the two dorsal 

 carirue, arching to the middle in an elegant curve, and meeting in the conical lumbar 

 spine. The two pectoral spines are short and nearly lateral, as are the two alvine ; 

 both pairs are mutually severed by a broad and deep excavation of the ventral surface 

 of the lorica, while a similar sinus, less deep, bounds each of these pairs on the right 

 and left. The flat ventral surface bulges out abruptly to form the pectoral spines. The 

 head is very large, and is composed of many globose lobes, each of which carries a 

 group of rotating cilia. An ample brain carries a small horizontal antenna, and a large 

 cervical crimson eye. The trophi are frequently seen to protrude obliquely from the front, to 

 nibble the floccose matters on which the animal feeds, which are, I think, exclusively vege- 

 table. The alimentary canal, large and very sacculate, following a short oesophagus, carries 

 two ovate clear glands, and leads (apparently without division) to the cloaca. In an 

 experiment, it readily received carmine. An ovary often shews embryonic vesicles ; and 

 sometimes a great maturing egg adds to the size and to the beauty of the animal. The 

 lorica is elastic ; in looking up along the cleft I have distinctly seen the ridges approach 

 and recede, sometimes nearly closing up and then gaping widely. The latter is coin- 

 cident with retraction of the head-parts, and at the same time some of the viscera are 

 forced up between the ridges, considerably above the level of their basal line (fig. 1). 



Though active, it does not swim much. It chiefly courses up and down among the 

 roots of the duckweed, which it affects, examining each in detail. It is not very 

 sensitive to alarm, caring little for taps or jars upon the instrument. The toes are 

 often expanded and closed. It is nearly colourless. P.H.G.] 



Mr. E. C. Bousfield has seen a male Salpina attached by its penis to a female which 

 was probably S. mucronata. It seemed to him that the male organ pieroed the ventral 

 surface of the foot at the base of the first joint. This appearance was doubtless due to 

 the male's adhering externally by the broad end of the retroverted penis. Dr. Plate 2 

 says that the male of Hydatina senta pierces the female, anywhere, with its penis. He 

 admits that he has never seen the organ within the female's body, and that he never 

 could find any aperture after the apparent penetration ; but suggests that the cilia of 



1 The dorsal fissure is not of fixed width, but variable at the will of the animal. An example (not 

 quite mature) of S. brevispina, which was sitting quite still, end-on, so as to give me an excellent 

 sight, had its dorsal cleft rather wide open ; while I looked at it, it deliberately closed up the sides to 

 mutual contact. 



2 Jenaiscli. Zcits. f. Natur. 1885, p. 37. 



G 2 



