History of the Hairy -backed Animalcules. 395 



C. larus may be identical ; but surely without good reason. 

 He has added a good deal to our knowledge of its minuter 

 anatomy; in particular he does not find the bristles of equal 

 lengthy but longest on the back and hind end ; and states that 

 each is a pointed spine furnished with two minute subordinate 

 spines, one springing on each side of its base. These spines are 

 processes of the skin, not hairs inserted into it ; but they are 

 dissolved by potass more readily than the skin itself. The 

 belly surface is quite destitute of spines, but it is uniformly 

 clothed on the anterior half with short cilia, which on the pos- 

 terior half are ranged in two bands along the edge, uniting 

 above the fork. The median line of the belly is clothed with 

 a row of short stiff down lying backwards. 



The mouth, surrounded by eight or ten long, soft, and 

 immoveable slender hairs, is formed by a circular membrane, 

 either finely plaited, or beset with minute prominences ("teeth" 

 Ehr.), protrusile, in the form of a short tube. Schulze recog- 

 nizes the great egg with its germ-vesicle, and adds that it is 

 covered with a shell, which potass does not dissolve. He also 

 finds in front of the ovary a cellular spermatic gland, and two 

 groups of spermatozoa ; but fails to detect any trace of nerves, 

 muscles, water-vessels, or tremulous tags. 



In August, 1851, I found in a dyke near Stratford a very 

 large Ohcetonotus, which I am disposed to refer to this species. 

 Its length was l-70th of an inch, its greatest width 1 -400th 

 (but including the bristles 1 -300th) ; length of the toes 1 -580th. 

 The dimensions, equal to those of a full-grown Notommata 

 aurita, rendered it distinctly visible to the naked eye, and 

 marked it from all others known to me. It was equally marked 

 by its dense coat of rigid, spinous bristles, set all over the body 

 on the upper surface and sides, and which are longer towards 

 the hinder parts. The toes are small, slender, slightly knobbed 

 and incurved ; they can be made to approach, and even to 

 cross each other. On the anterior half of the body the bases 

 of the bristles are evidently set in quincunx in about eight rows 

 visible ; the spots are very distinct and strong. On the pos- 

 terior half, the increased length and decumbency of the bristles 

 cause a brown opacity and roughness ; through which, however, 

 the cylindrical intestine can be seen by focussing. The head 

 is but slightly lobed, and the neck scarcely at all constricted. 

 The mouth consists of a short tube, evidently protrusile, with a 

 dark oval speck at the bottom in the centre, where a straight 

 slender tube originates, and passes through a wide cylindrical 

 oesophagus to the intestine, the head of the latter embracing 

 its fundus. On the front and at each side of the head are 

 very delicate curved hairs like vibrissa?. Just below the lower 

 edge of the mouth are placed two minute hooked organs, the 



