72 . PACHYMENIA ABYSSORUM. 



Limifossor fratula, sp. iiov. 



This species is represented by two individuals taken off the coast of southern 

 California (Sta. 43G9) at a depth of 260-284 fathoms. In general it so closely 

 resembles the foregoing species that a very bripf description will suffice. The 

 body, slaty gray in color with a slight yellowish cast, is shorter and thicker than 

 in L. talpoideus, and owing to a heavier body wall is much firmer. The spines 

 of the two species are very similar in form, but in the present species they are 

 of considerably larger size. Spicules from the middle of the body are 0.5 mm. 

 in length while in L. talpoideus the largest of the body do not exceed 0.38 mm. 

 The hypodermis is also proportionately thick and what are probably matrix 

 cells ai'e frequent and sharply differentiated from the other elements of the 

 hypodermis, and hence different from L. talpoideus in this respect. 



The digestive tract in the two species is, neglecting minor differences, 

 built upon the same plan. Heavy as is the radula and its supports in L. tal- 

 poideus it is even heavier in the present case, and the teeth are of larger size, 

 making it so difficult to section them that at present there are no clear indications 

 of their exact shape though it appears certain that the smaller cusp of each tooth 

 is larger than in the preceding species. The muscles that operate the radula 

 are typical but are unusually heavy. 



The nervous, circulatory, and reproductive systems are very similar in the 

 two species. 



This species is readily distinguished from the foregoing by the size of the 

 spines, the structure of the hypodermis, and the heavier musculature and con- 

 sequent firmness of the body. 



Pachymenia abyssorum, sp. nov. 

 One specimen of this species was dredged off the southern coast of Cali- 

 fornia (Sta. 4397) in 2196-2228 fathoms, the greatest depth recorded for any 

 Solenogastre. In bringing the animal to the surface the conseciuent decrease 

 in pressure upon the body resulted in the active release of gases from the blood, 

 causing the displacement of the cuticle to a considerable extent, the shrinkage 

 of the hypodermal cells and the partial destruction of the foot at various points; 

 otherwise the tissues are in a good state of preservation. The body is thick 

 set, externally resembling Alexandromenia valida, and measures 27 mm. in length 

 by 4.5 mm. average thickness. The color is a light yellowish white. As is 

 indicated (Plate 39, fig. 4), the foot is exposed for a considerable distance, and 

 is unusually broad and doubtless in life is capable of forming a relatively large 



