SALPINADA. 83 
long side (the dorsal) unsewn, whose edges remain approximate, yet separate.! 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 spmes.—P.H.G.] 
8. mucronata, Hhrenberg. 
(Pl. XXII. fig. 1.) 
Salpina mucronata rs . s Ehrenberg, Die Infus. 1838, p. 469, Taf. lviii. 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 
carine, 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 ashort esophagus, 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 pierced the ventral 
surface of the foot at the base of the first jot. 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 
» 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. 
* Jenaisch. Zeits. f. Natur. 1885, p. 37. 
