COCKERELL : ON THREE NEW NUDIBBANCHS. 87 



Thecacera velox, n. sp. 



Length about 12 millim., narrow, general form of T. iiennigcra. 

 White, marked with black stripes, appendages tipped with orange. 

 Foot tentacles and oral tentacles both long, the first white with a 

 purple-black line beneath, continuous with the lowest body-stripes ; 

 oral tentacles with the apical three-fourths bright orange. Rhinophores 

 laminated, with a terminal finger-like process ; apical third (including 

 more than half of the laminated portion) bright orange. Rhinophore- 

 sheath taking the form of a thickened tentacle, about as long as the 

 rhinophore, lateral of the rhinophore and curling behind it ; this 

 pseudotentacle is purple-black above and white beneath, with the end 

 broadly orange ; the anterior lobe of the sheath, found in T. pennigera, 

 is wholly wanting in T. velox. Appendages latero-posterior to branchiae 

 formed as in T. yennigera, with the apical half orange (a small black 

 spot beneath at the base of the orange), the upper side, from the base 

 of the orange forward, with a broad purple-black stripe, these stripes 

 passing forward and joining in the middle line of the back anterior to 

 the branchiae, thence sending a short process forward, and another 

 backward on to the median branchial plume, meeting the orange of 

 its extremity. Branchial plumes three, about as in pewn^V/era, bipin- 

 nate, the lateral ones with a purple-black patch and a little orange 

 mark beyond ; the middle one broadly orange at the end. Hind end 

 of foot bright orange, the black bands stopping abruptly at the orange. 

 The purple-black longitudinal stripes are a dorsal and two on each 

 side ; the dorsal begins very broadly on the front of the head, and 

 thence narrows until it ends some distance before the branchiae ; pos- 

 terior to the branchiae it is continued, and goes nearly to the end of 

 the foot. The subdorsal stripes are interrupted in the region of the 

 branchiae, but otherwise are nearly entire. There are very short 

 stripes in the area between the dorsal and subdorsal stripes, about the 

 middle of the anterior part of the back. The lateral stripes border 

 the narrow sole, and are continuous, but end before the subdorsal 

 ones. 



Hah. — La Jolla, San Diego County, California, among rocks at 

 low tide, August 3, 1901 (Helen Blake). Very active when swimming 

 with an undulating motion on the surface of the water. Described 

 from a living specimen. 



