WITH NOTES ON THE WEST INDIAN SPECIES. 



277 



5. Spengelia alba n. sp. 



Colour, Measurements and External Form. 



This species is remarkable on account of its almost uniformly dull white colour. 

 During life the proboscis and collar were opaque white ; the anterior free portion of 

 the collar was plain white, and was followed by a watery white zone ; then came a 

 white ridge, followed by another watery white zone, which was separated by the usual 

 circular groove from the posterior white band of the collar. In the hepatic region 

 there were green and brown tints. 



The proboscis when extended attained a length of 10 — 11 mm. (after preservation 

 8 mm.), and was cylindrical in shape. The collar under the same conditions attained 

 a maximum length of 6'5 mm. (after preservation 4 mm.). 



Behind the branchial region the trunk appeared to have a ventral curvature 

 impressed upon it, and the ventral side of the body in the hepatic and abdominal 

 regions was distinctly carinate, the median tract being marked off, on each side, by 

 a deep longitudinal groove, from the rest of the body (PI. XXVII. Fig. 9). 



The branchial region, 18 mm. in length, is characterised by the elongated, even, 

 band-like gill-area. The body in this region has a transverse diameter of 3'5 mm., 

 and a vertical diameter of 4".5 mm. The entire body of the animal may be described 

 as long and slender. 



The genital region, 25"5 mm. in length, is characterised externally by the presence 

 of dermal pits which are very similar in superficial appearance to the corresponding 

 structures in 8. j^orosa ; but in section they are found to be much shallower. 



The hepatic region, characterised by its green and brown coloration, had according 

 to my notes a length of 14 — 15 mm. The effect of preservation was to cause this 

 region to lengthen rather than to contract and in the preserved condition I should 

 put the length of it as nearer 20 mm. There are no external liver saccules although, 

 when fresh, the annular ridges were found to be turgid and to present the appearance 

 of rudimentary saccules, an appearance which was almost entirely lost after preservation. 

 Nevertheless even in the spirit specimen some of the dorsal annular ridges of the 

 anterior portion of the hepatic region tend to be more pronounced than the ordinary 

 ridges. 



The hepatic region is above all characterised by the presence on each side of 

 the body of a smooth glandless epidermal tract lying nearer to the ventral than to 

 the dorsal side of the body. It commences in front, at the posterior end of the genital 

 region as a wide area quickly narrowing down to a narrow streak, which widens out 

 again to a breadth of about 1"25 mm. in the mid-hepatic region. From the region 

 of maximum breadth it gradually narrows down posteriorly and is continued for 

 some distance into the abdominal region (PI. XXVII. Figs. 9 B and 9 c). 



In the fresh state I observed brown loculi showing through this ventro-lateral 

 tract in its wide portion, due presumably to the local turgidity of the gastral wall. 



