3QQ DAVID BRYCE ON THREE NEW SPECIES OF CALLIDINA. 



a development which is probably directly connected with the 

 *' domestic " habits of these species. In most cases, however^ 

 the upper lip is represented by a shallow area, whose anterior 

 margin is subject to astonishing variation. It is therefore the 

 outline of this anterior margin which is referred to in descrip- 

 tions of the upper lip. While experience has shown that one- 

 must not absolutely rely upon the constancy of this outline, it 

 has also shown that variation therein is most infrequent among- 

 individuals of one species, whilst there is scarcely any other detail 

 with so wide a range of variation when one species has to he- 

 compared with another. 



To some extent the outline of the anterior margin appears to 

 vary according to the proximity to each other of the two pedicels. 

 If these are adnate, as in Hahrotrocha jnisilla and other species- 

 with very small coronae, or closely proximate, as in If. constricta^ 

 (Jalliclina Ehrenhergi and others, the upper lip is usually centrally 

 prominent or high, frequently attaining to the level of the discs- 

 surmounting the pedicels. When, however, the pedicels are 

 widely separated, as in the four-toed genera, Philodina and 

 others, the upper lip is usually of moderate height, seldom rising 

 more than about halfway up the pedicels. On the other hand,, 

 whether the pedicels are proximate or remote, several species 

 have an upper lip, which is decidedly low, either showing a 

 slightly convex outline or having a very obtuse median angle. 

 In such cases, when the pedicels are moderately or widely 

 separated, it sometimes happens that the nexus which connects- 

 the pedicels, usually at their base, is left exposed in place of 

 being hidden. Again, when the pedicels are rather or very 

 widely separated, the upper lip is most usually carried forward 

 between the pedicels towards the ventral side. 



These several forms are complicated by another line of varia- 

 tion, which seems to have deeper significance than the variations 

 of height, and which possibly has no real connection with them. 

 Whether the upper lip be high or low, it is, with few exceptions,, 

 more or less obviously bilobed if the species belong to that section 

 of the Philodinidae in which the lumen of the stomach is tube- 

 like. If, on the contrary, the species be a pellet-making form,, 

 with the usual more bag-like lumen, then the upper lip is, and I 

 think without known exception, simple and undivided by the 

 faintest furrow or notch. When it is bilobed, the lobes are in. 



