^^ LUCERxXAKLE AND THEIR ALLIES. 



36 Color -The divers tints of the body range very widely, from a dark purple 

 to an uhnost glasW green, and, even in the brownish colors, are always hgbted up 

 by a sort of opalescent play of varied intensity. Locality does not seem to have any 

 iniiuence here, for totally different hues are represented, side by side, in the same 

 tide pool an.l even upon the same blade of eel-grass. In any case the body is 

 uniformly of one color, either all blue, or green, or olive, or yellow, or orangey very 

 rirely red but occasionally pink or violet, and from that it ranges in different 

 individuals to a dark purple, or purplish brown. In very rare mstanccs the color 

 varies in different parts of the body. 



§ T. The Prohosds. (PI. i, firjs. 1, 2, 3 ; PI ii, fi'J- 22 ; Tl. iii, fig. 3T ; 



PI. iv,/</. 50.) 



37. The proboscis is not only typically, but actually, topographically, the anterior 

 division, the foremost of the cephalic members of the body. In neither sense, 

 though, is it distinctly separable from the umbellar region; the latter and the 

 former insensibly shade off into each other, and, as it were, mutually overlap at 

 alternate points. Generally speaking, the proboscis is quadrilateral from two 

 different points of view (.A>. 1, '2, 3, and 37 p), and so nearly alike in length and 

 breadth that it has the contour of a cube, or of a very short quadrangular prism, 

 the corncu-s of which lie, respectively, two in the vertical axial plane of the body, 

 and two, at ninety degrees from these, in the horizontal axial plane. The four 

 sides of this organ, therefore, face obliquely at forty-five degrees from either of 

 these planes. Viewed from the front {fi<]s. 2, 3, 22), as the animal rests in the 

 conventionally honiological position for comparison, the proboscis presents a 

 cruciate appearance, the angles forming the four extremities of the cross, thus +, 

 the perpendicular arms of the cross corresponding to tlie vertical axial plane, and 

 the horizontal limbs to the horizontal axial plane. Such are the outlines of this 

 organ, in the main, but we must now particularize the several features, one by one, 

 in order to complete the details of our topographical sketch. 



38. The mouth is bordered by the four terminal smooth edges of the right and 

 left sides of the proboscis {firj. 22 p) ; it is, therefore, quadrilateral also, but is 

 modified more or less by the longitudinal plications and inarchings of these 

 edges, so that, with varying degrees, it presents, from time to time, all of the 

 intervening outlines between a rectilinear quadrilateral and a spherical quadri- 

 lateral. It is, moreover, altered in shape by the replication or rolling outward of 

 the edges {fig. 1), or by their mutual approximation. There is no demarcation 

 between the buccal orifice and the buccal cavity which is -included between the 

 tour flanks of the proboscis ; nor is the latter space separated by any intervening 

 object from the post-buccal (^«) or central umbellar chamber, which lies imme- 

 diately beliind it ; the two latter insensibly run into each other, in the same way 

 that the external contours of the proboscis and tlie umbel mutually blend. 



39. The hmal region of (he proho.^^cAs is by far the most remarkable part of that 

 organ, and is so singularly constructed that it would be impossible to describe it 

 apart trom tlie anterior umbellar floor, with which it forms a direct continuation. 



